Cast Blaster Public Beta is NOW AVAILABLE (but does NOT support USB soundcards - argh)
Direct link here
According to the forum:
You can order a license at http://www.shareit.com/product.html?productid=300031272 and use it both for this beta and for the final release version 1.0.
CastBlaster :: View topic - CastBlaster v0.17 beta
Update: I can't believe it doesn't support USB soundcards. All these podcasters talk about needing great microphones, etc - so you go out and buy something like the M-Audio and you find you can't use it. Very frustrating. Not sure - why this is such a tricky thing to support.