Major Nelson Podcast http://majornelson.com/archive/2010/12/19/show-381-call-of-duty-black-ops-dead-money-and-bf-bc2-heads-to-vietnam.aspx, revealing a few new tidbits on Dead Money.
-Takes 4-6 hours to beat
-Each companion has their own perk, can only take 1 at a time
-Veronica has new dialogue options after you beat the DLC and can get 1 of 2 new perks depending on what you say.
-Ghost People apparently need to be decapitated or gibbed to be killed; Shooting them elsewhere stuns them.
-The Nightkin companion is schizophrenic and has two personalities, Dog and God. Both have their own perk.
-The human companion is named Christine, and is described as mute but intelligent.
-The ghoul companion is a lounge singer named Dean. You may have seen him on posters or load screens in the main game.
-New weapons include the Holo-Beam and the Beartrap Fist.