The LE version comes with everything (or some stuff) unlocked, so in the standard version you have to level up to unlock stuff.
The Limited Edition version of BC2 comes with 6 unlocks (4 unlocks for BC2 and 2 for BF1943)
Bad Company 2:
Four vehicle warfare unlocks
Improved Vehicle Armor - An up-armor package is mounted on all vehicle types, decreasing the effect of both explosive and penetrating warheads, significantly improving vehicle survivability.
Supreme Vehicle Firepower - Additional weapon packages are mounted for the driver of all armored vehicles, greatly expanding the range of targets the vehicle can successfully engage and destroy.
Vehicle Motion Sensor - Use this electronics warfare package to locate enemy units in direct proximity to the vehicle.
Tracer Dart Pistol - This magnetic dart attaches to any vehicle surface, allowing squad members to track, lock on, and fire rockets onto moving targets even beyond line of sight.
Battlefield 1943
M1A1 Submachine Gun - Reliable but heavy this classic weapon is a powerful force in the hands of any Battlefield veteran.
M1911 Pistol - Highly customized M1911 are favored for its dependability and the power of its large .45 caliber round.
http://investor.ea.com/releasedetail.cfm?ReleaseID=419704