Here are the Perks that will star in Modern Warfare 3:
Perk Tier / Slot OneExtreme Conditioning: Sprint longer distances (like Marathon). Extreme Conditioning Pro will allow you to climb obstacles faster (like Marathon Pro).
Sleight of Hand: This will allow you to reload faster. Sleight of Hand Pro will allow you to swap weapons faster.
Scavenger: Just like in MW2, Scavenger will allow you to refill your ammo from fallen foes in MW3. Scavenger Pro will allow you to spawn with more ammunition than normal.
Blind Eye: This will make you undetectable to support (killstreaks etc). Blind Eye Pro will allow you to lock onto air craft much more quickly. It will also allow you to cause more damage against enemy air support.
Recon: If one of your explosive weapons causes damage to an enemy player, that enemy player's position will be painted on the minimap so that your team mates instantly know where he is. With Recon Pro, shooting an enemy with regular bullets will paint his position on the minimap so that your team mates know where he/she is.
Perk Tier / Slot TwoHardline will work like it did in Black Ops and Modern Warfare 2. i.e. you'll need one less kill / point for a killsteak / pointstreak in MW3. Hardline Pro will allow 2 assists to count as a kill towards your killstreak.
Assassin will act like a watered-down version of Cold Blooded/Ghost. It will make you immune to UAVs, Heartbeat sensors, Portable Radar and Thermal. It will NOT make you immune to air support and killstreaks. Assassin Pro will make you immune to the Counter UAV and the EMP.
Overkill will allow you to select a primary weapon as your secondary weapon. Basically, Overkill will allow you to have two primary weapons in MW3. Overkill Pro will allow you to put two attachments on your secondary weapon, much like Bling Pro in MW2.
Quickdraw in MW3 will work like Sleight of Hand Pro in MW2 and Black Ops. It will allow you to aim down your sights at a faster rate. Quickdraw Pro will allow you to recover faster after using your grenades or equipment.
Blast Shield was a piece of equipment in MW2. In MW3, Blast Shield will be a perk. It will allow you to take less damage from explosives. Blast Shield Pro will make you immune to flash grenades and stun grenades.
Perk Tier / Slot ThreeSitrep in MW3 will work the same as Sitrep in MW2 and Black Ops. It will allow you to see enemy explosives and equipment. This is like Bomb Squad in COD 4. Sitrep Pro will allow you to hear footsteps better.
Dead Silence will work like Ninja Pro. It will make your footsteps almost silent. Dead Silence Pro in MW3 will prevent you from taking fall damage, much like Commando Pro in MW2 and Lightweight Pro in Black Ops.
Stalker will allow you to move quicker while aiming down your sights. Stalker Pro will delay claymore explosions in MW3.
Marksman will give you an ID target from Ranger. I'm not really sure what that means yet. Marksman Pro will allow you hold your breath for much longer while scoping through a sniper rifle or a thermal scope.
Steady Aim will give you increased hip fire accuracy. In MW3, Steady Aim Pro will allow you to quickly aim down your sights while sprinting. This is similar to Lightweight Pro in MW2.
Please note that all of these perks are subject to change.