Todd Howard recently did a podcast at Kotaku. He didn't really say much about Fallout: New Vegas, but there are some interesting bits. First up, Howard mentioned that they're still going to use the Gamebryo engine for their next game (whatever it may be), but they'll have to update the animations and graphics a bit.
Second, when asked about Obsidian and Fallout: New Vegas:
They're going to do what they're going to do. I think it's in very good hands, and they know the world pretty well considering that some of them helped make it. That's all I can really say about it.
I take that to mean that Obsidian has pretty much all creative control and hopefully they're changing and fixing a lot of what was wrong with Fallout 3. We'll have to wait until OXM's February issue comes out to see I guess!