It looks as though EA have stuck to their projected release date for the Vietnam expansion pack, as Steam are currently listing Battlefield Bad Company 2 Vietnam on their product page with a valid launch date.
Usually, you would take this kind of information with a pinch of salt. And I encourage you to do so until we have an official press release stating otherwise. Steam have listed the release date as December 18 2010.
UPDATE: Battlefield: Bad Company 2 Vietnam now has an official release date — December 21, 2010, although PC users will still get the game “exclusively” 3 days early. VIP Map Pack 7 will come out December 1, 2010.
Purchasing from Steam will cost you $14.99. You can also pre-order via the EA Store too. If you do decide to go with the latter, you can expect to get the game three days earlier which would mean a December 15 release date. We are not sure if this applies to Steam or not.
Regardless of release date, the patch for BFBC2 was released today which can only mean that we are not far away from launch now. More information regarding the patch can be read here. It is a massive 2.6GB big, giving us more reason to believe it holds pre-content for Vietnam.
Will you be purchasing the Vietnam expansion pack?
Also See: Steam Summer Sale dates leaked for 2016