Why your podcast is probably already illegal
By a strange series of links (starting with Scoble's Crossfader post), I see (via Mark May) that ASCAAP has updated its latest internet license to include a reference to podcasts. So podcasters are explictly included among those expected to shell out to play music. If you're not paying up right now, you're out of compliance. (Thus if the Grokster ruling is for MGM, the companies whose products you use to produce those 'casts would be liable for your actions, right?)
Mark figures the bill comes to $750 to performing rights organizations like ASCAAP, $42.50 per track to Harry Fox Agency for "mechanical rights" and a mystery figure you need to negotiate with the labels for "master use license" (they don't have to agree to give you the license either).
(Oh, btw, Crossfader is "a new online educational and collaboration community for electronic artists. Built by artists for artists, Crossfader will help you learn about the tools of trade [sic], promote your style, experience new genres and stay ahead of the technology curve.” Via Greg Yardley.)