I’ve been working on Radio UserLand for Macintosh. I think it’s almost ready. When it is, the link above will go to the download page. (Actually it already does, but the Mac version isn’t available just yet.)
It supports seven players, including Audion, QuickTime and SoundJam.
It also includes all the features of the Windows version. In fact, in some ways I think it’s better, since it has a more stable playback engine, that doesn’t use a web browser to get playback going.
Check out the Macster Weblog’s discussion group to see how the development process is going.