Was any progress made in creating some kinda of umbrella licensing agreement regarding podcasts? There was talk of something along those lines... It's possible that the bandwidth costs of providing podcast downloads would be lower than having to setup something that is streaming 24x7.
There is plenty of music that would one could podcast that dosen't fall under the RIAA, might still have to pay a fee to ASCAP, BMI. Or you could also take the time to obtain permission from the artist for use in a podcast. But that would be time consuming... Or just do and hope nobody catches you, not a risk worth taking IMHO.