If you upgraded any of your photo- and music-filled macs with Tiger (OS 10.4) in the past month, you've probably realized like I did that suddenly your TiVo can't see your mac. I was wondering why my setup behaved this way, and to my surprise, I found the answer: the current TiVo Desktop software does not work with Tiger (the installer crashes at the end).
But a cursory glance at the TiVo Community boards reveals that someone has produced a GUI app that enables your TiVo to once again see your upgraded mac. It sounds like it entailed some shell scripts that modified the way TiVo Desktop talked to the rendezvous/bonjour network and updated the XML format used by the software.
I'm kind of surprised that this fan-contributed app has been done and working for a month and TiVo still hasn't incorporated the changes into its own software yet, but this is another great example of the TiVo hacking community stepping in to fill a need. If you've upgraded your mac, this is currently the only way to see your photos and hear your music again.