Recently I've been approached by two different people asking for permission to podfic stories of mine. I was flattered they found them interesting, and it would never have crossed my mind to say no -- nor did I expect to be asked for permission. My feeling is once the story's out there, it can be recorded, critiqued, archived or whatever. If I don't like their version, I'm free to do my own. I would not, however, like to discover a work of mine had been abridged for a podfic unless it was just a finite chapter being recorded. I think a podfic exists as a collaboration between writer and reader.