TiVo's just released a new public beta for Series 2 and Series 3 owners, adding various transcoding and broadcasting features. For S3 owners, they can now send HD photographs (1280x720) for viewing on their TV, and for S2 owners, they can transcode various video formats into TiVo-format so you can watch that on your TV as well.
Unfortunately for everybody, TiVo's locked out DivX (and presumably XviD), so all your downloaded movies need to be transcoded into something else before they can be transcoded again into something TiVo can play. Lame, TiVo. Lame.