The following content is now available on the Xbox Live Marketplace.
Trailers:
Battlestations Midway
Eragon
Import Tuner Challenge
Need for Speed Carbon
The Darkness
Demos:
FEAR
Picture Packs:
Mass Effect Picture Pack $ (Premium)
Battlestar Galactica (US Only)
Videos:
TGS Showfloor video 3
Edit: The Mass Effect Picture pack is free. My error.