Pictured above is Too Human from Silicon Knights, a very impressive action game that should be dropping next Christmas. I haven't found a high definition trailer yet, but a low res trailer and some beautiful screens are available.
Mass Effect: The high definition trailer is only available on IGN that I've been able to find so far, and only for Insider subscribers, but if you can wait, it will probably be up on Xboxyde or Game Trailers later.
Tomb Raider also makes a comeback in glorious HD, courtesy of GameTrailers and Xboxyde.
Last but not least is the Splinter Cell 4 footage, very short, but very sharp and very deadly.
Just as I went to post this, Xboxyde posted this picture of NFS: Most Wanted, so I don't think the well is dry just yet.