It's there on the horizon, like a mountain range I know I will some day climb. I spent a few hundred hours on Fallout 3, and I expect to spend the same on Fallout New Vegas.
Much like the "GTA 3" is succeeded by "Vice City" ('GTA 3 Vice City'), I think of Fallout 3's successor to be 'Fallout 3 New Vegas', even though they just call it "Fallout New Vegas". I hate it when a series mixes numbering and naming systems (like Windows).
Anyway, soon. Just a little bit more Real Life crap to flush, then we're going to be at the base of that mountain range, looking up.