Mac Geekery has a detailed how to on how to save TiVo recordings so that they can be viewed on a Mac or an iPod.

Unfortunately, you need to:

• Install and set-up Galleon
• Build an application called TiVo decode
• Set up a conversion script
• Set up launchd
• Transcode the video to a compatible format
• Sync it to your iPod

It’s not for the faint-hearted and probably violates the Digital Millenium Copyright Act half a dozen ways, but the fact that someone will jump through these hoops shows that there is an audience that wants to time- and space-shift video really bad.