Okay, let's look at some data to begin with.
First, when do we expect Uncharted 2 to release? Early December, like the first game? October, like in that thread from the random guy who claimed to have gotten an email (and promptly left out inFamous...)
Let's go with December 2nd, around the same time Uncharted released, on a userbase of ~9 million PS3s. GameStop broke the release date (the pricks), and so we got some pretty skewed first week sales:
Week 1 16,494 32,289 85,100 133,883
Week 2 9,764 54,342 110,708 174,814
Week 3 7,441 42,087 129,378 178,906
Week 4 6,153 44,224 83,792 134,169
Week 5 7,002 45,105 53,486 105,593
We can assume that won't happen again. Also, let's assume a userbase of 29 million PS3s when Uncharted 2 comes out.
I think that Uncharted would have done around 400k first week, if the release was not messed up. So, I say 750,000 is reasonable, though it could be as low as 500k. It should see some very good holiday sales, like the last game, and could be anywhere from 800k-1 million by year's end.
Of course, it depends on userbase, advertising, release date and competition.
(Former) Lead Moderator and (Eternal) VGC Detective 
