Update: though EA/DICE have said the early DLC was compensation, the exclusivity has actually been planned since at least September.
Update: it turns out the early access is due to the cancelation of a previously announced deal whereby a free copy of Battlefield 1943 would be offered to those who purchased Battlefield 3 on PS3.
PlayStation 3 owners will be getting the Battlefield 3 expansion Back to Karkand one week earlier than other platform users -- a definite kick in the pants for some, given it's a quasi-remake of Battlefield 2, a PC-exclusive game. As mentioned previously, Karkand will launch sometime in December.
To ease the pain a bit (or perhaps make it worse), we've a new gameplay trailer featuring yet more scrumptious Battlefield moments:
Moving on, Assignments are one of the key features in the expansion. These are goals you must achieve to unlock weapons and dog tags. For example, the "Let it Rain" Assignment dictates you must rack up 20 LMG and two mortar kills. Once you do, you'll be granted a new weapon and matching dog tags, plus access to a new assignment.
It's important to note Karkand will be fully integrated with the base game, so you can make progress on Assignments no matter what map you're playing on, and the new weapons can be used on any map. Map rotation, as well, will be fully integrated -- not like Bad Company 2: Vietnam. It's not precisely clear how this will affect users who don't have the expansion, but we'll know soon enough.