Over at the official 2k6 forum at 2ksports.com, they seem to have pointed to the new GI...along with some facts about the graphics...
For the xbox 360:
The xbox 360 version wont ship simultaneously with the current-gen versions, but 2k sports believes that it will be trailing only a few weeks behind, placing it in late march or early april. Like 2k sports first gen basketball foray, the majority if the additions to this version are of the graphical sort. The entire crowd ( which can strecth up to 60,000 people) will be fully modeled. If a foul ball is hit to a specific section, the fans will leap to their feat and jockey for position as they try to get their hands on the souvenir. Fans will also have the ability to get up and head for the bathroom. Vendors will make their rounds up and down the stairs, and you'll even see secruity guards on patrol. All of the stadiums in the game have been completely rebuilt for this version. Youll also see volumetric grass in the outfield and the most realistic dirt around. Much like the incredible cloth technology features in nba 2k6, the uniforms in this game will wrinkle and flow as the players move. New gameplay features are also being introduced, such as context-based moves like leaning over a railing to snag a fly ball. And yes, 2k is throwing around the idea of inlcuding a fan at wrigley that looks an awful alot like Steve bartman..
They also show 3 images..one of Derek jeter swining, him playing short stop and his face..all look amazing
and im sorry for any spelling errors, atleast i typed this whole thing out
enjoy