And you already missed it. Riley
's apparently got a pretty good eye, and wrote in with this:During an episode of The Tonight Show with Jay Leno last week, they sent some correspondant to the Grammys. During one of the interviews in the background you can see Trent walk by. I'm 99% sure its him. He's on camera for quite a long time, looking around. I'm not sure what episode, or who they were talking to at the time though... sorry.
Many people wrote in to point out that Wireimage.com
has photos online of Trent at a Grammy after party in addition to the backstage-with-Bowie photos. Just do a search for "Trent Reznor" to see for yourself.