Technical posts from the AVS BBS:
(as long as they last)
Topic: Hacking the Tivo
Topic: Upgrading 14hr TiVo
Topic: Has anyone tried to boot a PC using Tivo disk?
Topic: How I Upgraded My 14 Hour Tivo MYSELF!
Topic: Inside a 30 Hour TiVo
Topic: Upgrading the hard drive(s) Lets figure it out
Topic: Tivo/Linux/Self Upgrades/Research/suggestions
Topic: Oddities from the Tivo Linux source release
Topic: tivo Linux source code
Topic: Software hacking for TIVO (got off topic, not much tech info)
Dazzle Digital Video Creator (board for PC that will encode MPEG like Tivo)
All-In-Wonder card for PC does MPEG
Some limted technical info and comparisons:
The Linux source code, note that Tivo only uses Linux to boot, after that they completely take over with a new custom OS.