Some interesting tid bits I've picked up:
source: http://blogs.battlefield.ea.com/battlef ... -back.aspxBack to Karkand works seamlessly in conjunction with the base game. This means that you can bring these ten new weapons back to the base game. They essentially get added to your existing arsenal rather than being an either/or choice. Also, servers will have the ability to run map rotations with any mix of base game plus Back to Karkand maps. Further, the new layer of persistence with Assignments does not replace what is in the base game – it works in parallel with it. Since you will be able to join mixed map rotations, we will alert you if you don’t own Back to Karkand and try to join a server where one or more maps require Back to Karkand.
From DICE's Kalms on how they will prepare the servers for B2K:
source: http://www.fpsadmin.com/forum/showthread.php?t=24165There will be a game server release next week. We'll release the docs a bit ahead of time (friday?) Since it will be a new server release, you can go by the build ID to identify whether or not the B2K maps are available.
Post anything of interest you've picked up.