This is just a wild guess here, because technically Fallout 3 has already been announced by Bethesda a long time ago - even though they never got into details about it so far. But a Game|Life story this week does hint at an upcoming game announcement from Bethesda, expected to take place on November 1. And the writer also drops a clue about what that game might be:
"At any rate, we're getting info on a game that'll be announced on November 1. So please look forward to that date, upon which you will be informed of everything. You'll find out, for example, how I got a thick layer of desert sand all over my white Old Navy shirt. Suspense!"
His report comes as a result of a Bethesda Softworks event he attended in Las Vegas, which could explain the "thick layer of desert sand" oh his... wait, why would anyone wear a white Old Navy shirt at such an event? And just how "Old" of a Navy shirt are we talking about? Old enough to have survived in a wearable state since the time of the great Vaults?
Did I just say Vaults? Sorry, but I can't help making the connection with the Fallout sequel that Bethesda bought the license for in July 2004. And two years does seem like a long time to work on a game and not have something to show for.
Of course, other titles are also a possibility - such as the Oblivion add-on that was last rumoured to be coming as soon as November 21. So hold your horses, we'll know for sure soon enough.
(N.B. Archive text, links removed)