I don't think someone from Bioware would announce when the requirements will be released, seeing as the game is developed by Obsidian and published by Bethesda, and Bioware really has no connection to it...
But as far as I know, there has been no indication as to when the PC requirements will be available, though I'd imagine it will be some time before the release date, so probably in the not too distant future, though I really can't see the requirements being very different from Fallout 3's, seeing as both games use the same engine, and in fact, I can't see any signs of graphical improvements in New Vegas, if there have been, I'd say that the differences are certainly not major, so I'd say that if your computer can run Fallout 3 without problems, it should be able to handle New Vegas as well, of course, this is just an assumption on my part, I have not actually seen the game's requirements, so I can only speculate.
So if Fallout 3 played like Oblivion, maybe New Vegas will play like Fallout 3 then. If there was an increas from Fallout 3 from Oblivion, then roughly take the difference and add it to what Fallout 3 is then.
I don't think that would work, since Fallout 3 had a fair amount of graphical enhancements compared to Oblivion, though I could see that both games used the same engine, Fallout 3 still looked quite different. Now the graphical standards of New Vegas seem to be much closer to Fallout 3's than that game was to Oblivion, so if the requirements have increased, I'd imagine it will be a smaller difference than Fallout 3 was to Oblivion.