Craig Tanner (whom I have tremendous respect for) did a podcast on process of creating the RadiantVista Podcasts.
In the podcasts Craig mentions that he/they use an open source tool called Audacity for their audio editing.
I tried Audacity today and it's pretty good. I am not an audio guru so have no in depth knowledge of what to expect of an audio editor, but as far as I am concerned, audacity lets me do all the basics, select, play, cut, copy, paste, loop.
Tags: Radiant Vista, Podcasts, Craig Tanner, Audacity, Open source