“Just a few days ago, a revealing teaser of Autumn-bound Fallout: New Vegas, was shown by Bethesda Softworks. Well, more details on the game were bound to come, and they did, as summarized by PSN @ Home via info from The Vault – a Fallout Wiki…… ”
Fallout: New Vegas – Huge Details Blowout (via [...]

According to rumor from a “trusted” source an MMO is indevelopment for the Elder Scroll series and is due for realease sometime in 2011. It is also noted in the article that the game was supposed to be announced sometime last year.
Court Documents Show Bethesda’s MMO is Already Under Development (via Massively)

“Little is known about Fallout: New Vegas at this point, as information is scarce and both Obsidian and their publishers at Bethesda have been less than forthcoming about the Fallout spinoff. Because the game is being developed by Fallout 2’s original creators, it’d be more accurate to refer to Fallout 3 as the spinoff of [...]

“Game Observer conducted an interview with Ashley Cheng, Production Director at Bethesda. He answered questions about the Gamebryo engine, why they prefer it over other engines and the advantages it presented while making Fallout 3. Cheng also talks a bit about what inspired their designers while making Fallout 3 and what is in store for [...]