T-Mobile will be showcasing Riptide GP (along with some other games you don't have to pay any attention to) in their booth at E3 2011.
From what we hear, their booth is going to be set up like a 50's diner, and you can take a load off and relax in a comfy booth while they ply you with smoothies to drink and games to play. The booth is number 1447, and is near the center aisle, towards the back of South Hall.
If you're in town for E3, be sure to come by! Ralf and I will be stopping in from time to time, particularly on Wednesday afternoon.