The upcoming expansion to Bad Company 2, Bad Company 2: Vietnam, is rumored to be releasing on December 22nd. However, the number of maps it will include is still unclear.

It was originally announced to have 4 "maps", with support for all four gamemodes.

So far, only two maps have been revealed, leaving two more unnamed maps.

However, in a recent video interview with Battlefield community manager, he mentions that Vietnam will have two maps. This is most likely a mistake, as it contradicts previous annoucments.

A recent youtube video from a German blog shows that there five maps, as well as showing all of the awards.  

Vantage Point
Hill 137
Khao San Temple
Phu Bai Valley
Operation Hastings

Hill 137 and Phu Bai Valley have been announced, with Hill 137 confirmed to support rush, and Phi Bai valley supporting conquest. This doesn't necessarily mean they won't support the other modes, however.

If the rumored release date of December 22nd, we should be hearing about these other maps in the next two or three weeks.