Also: It's confirmed to be single player only. One other tidbit is that when asked about the sys requirements Beth doesn't give an answer possibly meaning that the game will have different requirements than that of Fo3.
Since a machine that could run Oblivion well can run Fallout 3 well I would say that New Vegas will be of the same level of requirements. Possiblly need more graphics horsepower to handle all the lights that Vegas is famous for. I would say that they are holding off on the requirements because they are still tweaking shaders and light sources. In the past games, the more lights there are in a cell (not actual lamps, but sources of light) the more performance is needed. Sometimes modding a cell to remove 50% of the sources would leave a cell that you could still see things in, just not as rich in color and shadow. However frame rates would more than double in those certain cells.
However if you can run Fallout now, I would venture to say that you could run Vegas.