Is Vietnam addon for Bad Company 2 a remake of an old BF: Vietnam game?

Well, it's a remake of 2004's Battlefield Vietnam only in the broad sense that it's a similar setting.

I do not think it's a true remake -- in the sense of having the same maps, same gameplay, and exactly the same vehicles and weapons as the 2004 game.

From what I have read, it'll be the same (awesome) core BF:BC2 gameplay, but transplanted to new jungle maps, vietnam-era weapons, and vietnam-era vehicles.

The [Vietnam] expansion pack will contain 4 new maps, 6 new vehicles, and 15 new weapons. It is also planned to include 49 contemporary music tracks which can be listened to via an in-game radio as well as new voice overs for both American and Vietnamese forces, based on authentic communication from the Vietnam war.