Chris Avellone posted a blurb on the Bethesda boards telling us some names of people we might know at Obsidian, as well as a few hints as to the plot and systems direction that Fallout: New Vegas is taking:
Question: You helped make Fallout 2, right? I think everybody agrees that Fallout 3 was different, but have you done anything to make NV be more like the first two? Or are you following in Bethesda's footsteps? To me it wouldn't matter either way. I'm just wondering.
Chris Avellone: Yep, I did area design and encounter design for F2 (worked on Vault City's third and final iteration, companions: Cassidy and Myron, special encounters, New Reno, Raider Camp, and the EPA, which got canned - and good thing, too, we already had too many locations) and some perk designs. Brian Menze, Feargus, Chris Jones, Scotty Everts, and Dan Spitzley are all here, all worked on Fallout 2, not all of them are on New Vegas, though.
The trailer is the only thing I can point to to answer your question, can't say much more than that. Josh and John Gonzalez (our creative lead and master of all things plot-related) put together a great story with some fun new mechanics, and they know their Fallout. I think we're using all the stuff we've been kicking around for the past ten+ years with RPGs and seeing how they can be applied to New Vegas on both the plot and system side.