Mary-Jo Foley, now perennial Windows Mobile leaker, has published some slides from when Windows Mobile 7 was still code-named Photon.
The slides talk about using broad stroke gestures to control slide shows, music playback or remote control. While these gestures sound feasible, Microsoft warns about battery drain, making it clear this is not a solved problem. Additionally the slides concentrate on using the back camera, when non-US users will know a front-facing camera is more conveniently placed.
See the slides below, and read more at the All about Microsoft blog.