From what I can tell, the tivo will work with the older Jerrold 7000 series decoder on Saturn.

Looks like it may natively control General Instrument decoder boxes too, if this is the case then the TiVo will control all the current Saturn Decoder boxes out in the wild. I'll confirm this when I recieve my TiVo this week (Has just been cleared by customs overnight by the looks of it).

Not sure at this stage wether it will work with controlling the digital stb's once digital cable gets under way. At this stage and with the info I know, I don't think it will.