Freevo, Not TiVo
The popularity of digital video recorders like TiVo seems to have gained momentum. So much so that now comes an OpenSource Linux-based competitor called Freevo (see it here).
I have not tried using it but it seems promising. The installation looks pretty straight forward but then, very little in Linux is straight forward. Yes, you need the hardware to run the program as well as get the TV signal into your box, but otherwise, it seems like it should work (famous last words - ed.).
There is even a Gentoo ebuild available for you Gentoo folks out there (you know who you are), although it isn't part of the portage tree yet. Go to the news page here and search for Gentoo to find the brief note. I don't know Gentoo that well but I assume the note tells you what you need to know to install, um, emerge it under Gentoo.