I think the FPS game shown off at the keynote will be available at launch or a little after. Apple's iWork apps (Keynote, Pages, and Numbers) along with the NY Times app might be available at launch.
It will likely take game developers a while before they start releasing iPad games that aren't just high resolution ports of their iPhone/iPod touch versions. It took a while for game developers to release iPhone/iPod touch games that just weren't ports of simple Flash games.