NBA 2K8/College Hoops 2K8
Most stores have this right now, and a few are breaking the street date (some Best Buys and Toys R Us have been reported as selling it).
Also, the demo is apparently out on the marketplace right now, though it is an older build of the game, which does not look nearly as good as the final release.
Anyway, last year's product was good, but ultimately broken as a competitive game, thanks to some major issues with the defensive system (specifically, the way the game reacted to blocks/charges, the idiotic and robotic nature of the defensive AI, and the fact that the spin move could not be countered consistently) and an offensive system that was marred by being too dunk-heavy and gimped with the same old passing glitches that have been around since NBA 2K on the Dreamcast.
That said, I might give this a try if the reviews are great.
Highlight video over at Operation Sports
