LucasArts has been running a playable demo of their upcoming Gamecube game "The Clone Wars" at Star Wars Celebration 2, a Star Wars fan orgy currently going on in Indianapolis, Indiana.
From the report at PlanetGamecube, The Clone Wars seems to be a ground-based action game which revolves around vehicles. The two levels demonstrated were a speeder-bike racing level, and a more combat-oriented tank level. Sounds like a (fun) version of Rogue Leader on the ground.
Update: I've been informed that The Clone Wars is more like Battlezone than anything else, if one were to draw a comparison. Don't know how they know that though...
Source: PlanetGamecube