MusicSafari appears to do it all for you without fiddling with the command line, editing audio files, writing AppleScripts, queueing cron jobs or whatever. It lets you choose AAC quality settings and gives you a dialog for placing scheduled recordings into iCal. It's US$20 shareware: The unregistered version only records 15 minutes at a time, so I haven't checked that it senses the end of a streamed file yet.
[robg adds: Though I only tested it briefly, this program appears to be the answer to one of the more popular email inquiries I receive.]

