I didn't spend my hundred hours of gaming time on Call of Duty 4 on the single player campaign and nor do I expect to spend more than the anticipated 8-10 hours playing the Modern Warfare 2 single player.  It's all about the multiplayer and here's all of the key information you need on the Modern Warfare

Modern Warfare 2 Online Multiplayer

Online play retains much of what is familiar to us from previous Call of Duty games.   Game modes available are Free-For-All, Search & Destroy, Demolition, Domination, Team Deathmatch, and Capture The Flag the returns and the action will take place across a number of locations based on the single player campaign.  An annoying feature of COD 4 was that when a host left, the game ended.  This is now fixed with in-game host migration, which should remove all instances of having to go back to the lobby and restart the game.

Modern Warfare 2 Online Kill Streak Rewards

Kill streak rewards also make another appearance, updated and extended from COD 4 and COD 5.  There are now up to 15 Kill Streak rewards spread out from 3 kills upwards.  Kill Streak Perks are unlocked and can be customised to each player, up to a maximum of 3 active at any time.  The default set is unlocked from launch and you can unlock the rest of them in any order.  As each is unlocked you can activate it for a game, giving you even more customisation options.

3 Kills – UAV - deploys a UAV showing enemy locations on the radar as red dots. The UAV can be shot down by the enemy and can be blocked with the Cold-Blooded perk.

4 Kills - Care Package - throw the red signal flare and a Care Package will be airdropped to that location but can be picked by anyone, including members of the enemy team.  Contains ammo or a random kill streak bonus.

4 Kills – Counter UAV – Disables the enemy UAV for a period of time.

5 Kills - Sentry Gun – An  XM312 Sentry Gun is dropped and will automatically fire at enemies. It can be destroyed by shooting it or blowing it up and Flashbangs/Stun Grenades temporarily diables it. Has a 360 degree turn and can shoot upwards or downwards. Sentry Gun is movable after deployed, but it won't fire while it is being moved

5 Kills – Predator Missile Strike - Remote control a Predator missile by opening the laptop giving you 5 seconds to direct it to your target.

6 Kills - Precision Airstrike - control the direction of the Airstrike for more accurate kills.

7 Kills - Harrier Strike – Call in an Airstrike from a hovering Harrier aircraft. Harrier drops it's bombs and then guards the area for a short period of time.

7 Kills - Attack Helicopter – Call in a helicopter to circle the map and automatically attack for a few minutes, but it can be destroyed with guns and missiles and will leave after a couple of minutes. Enemies killed are added to your kill count.

8 Kills - Emergency Airdrop - Airdrops 4 random killstreaks or ammo. Basically the same as receiving 4 Care Packages.

9 Kills - Pave Low - Deploys an armoured Sikorsky MH-53 Pave Low Attack Helicopter, a more effective and better helicopter than the attack helicopter on 7 kills.

9 Kills - Stealth Bomber - Call in a B-2 Spirit  Stealth Bomber to carpet bomb a selected area.  Kills are added to your tally and the airstrike doesn't show on enemy radar.

11 Kills - Chopper Gunner – Call in an attack helicopter but actually be the gunner as it flies around the map and you fire the 25mm gun.

11 Kills – AC-130 – Call in a AC-130 Gunship, which you control for 30 seconds to use the 25mm, 45mm and 105mm guns to shoot at enemies. You are vulnerable while controlling the AC-130, but if you get killed while using it, you can still continue until the 30 seconds is up

15 Kills – EMP – Fire an Electromagnetic pulse which disables enemy electronics temporarily.

25 Kills - Tactical Nuke - Gives your team an instant win, ending the match with a bang and killing everyone on the map.

Modern Warfare 2 Online Multiplayer Perks

Also back is the experience points system which unlocks perks and new weapons for use in online games.  As before experience points are earned for kills, fulfilling match objectives (e.g. capturing a flag, destroying a target, defusing a bomb) as well as completing objectives such as target number of kills with each weapon.  The perks and upgrades are what gives the Call of Duty series some it's addictiveness and enjoyability and the Modern Warfare 2 multiplayer looks no different.  Here's a definitive guide on the Modern Warfare 2 Perks, which again are split into 3 Perk Slots, with one perk allowed in each slot.  Once again the multiplayer perks are grouped so a player can't over strengthen themselves and players remain balanced and, importantly, there are multiple genuine upgrade options giving different styles of play and strengths.

New for the Modern Warfare 2 Multiplayer is the ability to upgrade a Perk to Pro status giving an additional, but related, upgrade to that perk.  Perks are upgraded to Pro by completing the challenge related to that perk.  This is similar to the challenges section of COD4 but this time the challenges will actually be used for something, which again will add to the depth and hours of play in the game.

Perk Slot 1

Marathon + Marathon Pro
Marathon Perk: Unlimited sprint
Pro Ability: Get over obstacles faster

Sleight of Hand + Sleight of Hand Pro
Sleight of Hand Perk Ability: Faster reloading
Pro Ability: Aim down the sights faster

Scavenger + Scavenger Pro
Scavenger Perk Ability: Resupply yourself from dead enemies
Pro Ability: Respawn with extra magazines

Bling + Bling Pro
Bling Perk Ability: Allows for upgrading primary weapon with 2 attachments
Pro Ability: Allows for upgrading secondary weapon with 2 attachments

One Man Army + One Man Army Pro
One Man Army Perk Ability: Replace your secondary weapon to change class
Pro Ability: Quickly swap classes

Perk Slot 2

Stopping Power + Stopping Power Pro
Stopping Power Perk Ability: Increased bullet damage
Pro Ability: Increased bullet damage against helicopters and aircrafts

Lightweight + Lightweight Pro
Lightweight Perk Ability: Move quicker
Pro Ability: Allows for quick aim after sprinting

Hardline + Hardline Pro
Hardline Perk Ability: Killstreaks require 1 less kill
Pro Ability: Death Streaks require 1 less death

Cold-Blooded + Cold-Blooded Pro
Cold-Blooded Perk Ability: Makes you undetectable by UAV, air support, Sentry Guns, and thermal sights
Pro Ability: No red crosshair or name appears on enemy screen when you are targeted

Danger Close + Danger Close Pro
Danger Close Perk Ability: Increases explosive weapons damage
Pro Ability: Increases air support damage

Perk Slot 3

Commando + Commando Pro
Commando Perk Ability: Do melee damage from a greater distance
Pro Ability: No damage will be taken from falling off buildings/objects

Steady Aim + Steady Aim Pro
Steady Aim Perk Ability: Hip-fire accuracy is increased
Pro Ability: Hold your breath for a longer period of time, for sniping.

Scrambler + Scrambler Pro
Scrambler Perk Ability: Jams enemy radar over a small radius.
Pro Ability: Delays claymore explosions

Ninja + Ninja Pro
Ninja Perk Ability: Invisible to heartbeat sensors
Pro Ability: Move silently - no footstep noise

SitRep + SitRep Pro
SitRep Perk Ability: Insertions. Reveals enemy explosives and Tactical Insertions
Pro Ability: Makes enemy footsteps louder

Last Stand + Last Stand Pro
Last Stand Perk Ability: Survive a normal death allowing you to shoot pistol from the ground. Lasts 10 seconds or less if you get shot again. You can now crawl in the Last Stand mode.
Pro Ability: Equipment like frag grenades and throwing knives can be used during Last Stand mode.

Modern Warfare 2 Multiplayer Weapons and Equipment

As in previous COD games, the Modern Warfare 2 multiplayer will feature a large range of weapons split into different categories: Primary Weapons, Secondary Weapons and Other/Equipment.  A lot of weapons from COD4 return, plus a few new ones.  As you progress through the experience points and ranks new weapons will be unlocked and made available.  Shotguns look to have been moved from Primary to Secondary.

Modern Warfare 2 Primary Weapons

Assault Rifles – M4 Carbine, FAMAS, SCAR-H, TAR-21, FAL, M16, ACR, F2000, AK47
Sub Machine Guns – UMP .45, KRISS Super-V, P90, MP5k
Light Machine Guns – RPD, M240, HK MG4, SA80 L86 LSW, Steyr AUG HBAR
Sniper Rifles – Walther WA 2000, SVD Dragunov, Barrett M107, Intervention M-200
Riot Shield – Riot Shield

Secondary Weapons

Machine Pistols – Glock 18, PP-2000, Mini Uzi, TMP
Shotguns – Franchi SPAS-12, Benelli M1014, AA-12, Winchester 1200, Winchester 1887, Armsel Striker
Handguns – USP .45, Desert Eagle, M1911, .44 Magnum, M9
Launchers – AT4-HS, Thumper, Stinger, RPG-7, Javelin

Other/Equipment/Attachments

Equipment – C-4, Ice Axe, Grenade, Smoke Grenade, Flashbang, Stun Grenade, Knife, Throwing Knife, Semtex.

Attachments – Red Dot Sight, EOTech Sight, ACOG Scope, Thermal sights, Suppressor/Silencer, Heartbeat Sensor, Laser Module, Rail Integrated System, M203 Grenade Launched, GP-25 Grenade Launcher.

Modern Warfare 2 Multiplayer - Special Ops

Special Ops is new for Modern Warfare 2 and puts the player in a Co-op mode scenario similar to that to the Mile High Club at the end of Call of Duty 4.  Spread out across the locations from the single player campaign the player can play alone or with someone else in co-op online play, either split screen or online.

Special Ops missions are grouped in Alpha, Bravo, Charlie, Delta and can be played through on 3 different level setting – Regular, Hardened and Veteran.  Completing a special ops mission on each difficulty will award the player a Star and new missions (of which there are 23) are unlocked when enough stars have been accumulated.

I'm excited about the Special Ops mode almost as much as the main online multiplayer.  It looks new and fresh and will add hours of game play on to the game even if each mission is completed once.  With statistics such as kills and time completed recorded for each Special Ops mission you do there is also the motivation to replay them and I would expect some kind of online leaderboard.

*All details are correct according to current information, as new details are released and confirmed this will be updated.