The long awaited Battlefield Bad Company 2 patch has been released today. Your client will receive the update on next launch.
According to this
forum post (External), the patch is roughly 500Mb in size.
Some highlights from the Changelog:
Gameplay - Knifing people in the back works again (we backed out the change that we had done for Server R11)
Gameplay - G36 now has crosshair when in Hardcore mode
Server Browser - Join queue system when attempting to join a full server
Server Browser - Now refreshes information
Client - Toggle/hold crouch is user controllable
Client - Toggle/hold zoom is user controllable
Client - New chat system allows chatting when dead (but not during end of round) and keeps a 100 lines log
Client - Any points you get while being dead will be added to your score
...