Americas region has a 5 to 3 ratio of 360's to PS3's, but still most 360 games out favor PS3 games by 2 to 1 or more (especially exclusives).
Mass Effect > Uncharted because a) sci-fi more popular in Americas, b) largely 360 oriented game, and again 5-3 360's to PS3's.
As for Halo and Gears, Americas gamers love multiplayer games more then the rest of the world. A lot more. Any good multiplayer games will sell well in Americas, even Call of Duty on PS3 is up there.
However what about non multiplayer multi console games? Well Elder Scrolls has a bigger base on 360 (since Elder Scrolls III was an X-Box exclusive, and IV was ported to PS3 late).
As for Rage and Deus Ex, they barely made the list for 360, with a much smaller install base, why would they make it for PS3?
The only game that's a bit off is Assassin's Creed. AC should have 140 or so pre-orders for PS3, maybe it's just off the list? I know PS3 games pick up more closer to launch, and 360 pre-orders typically pre-order strongly from announcement.