I think the idea is interesting - I played around with a prototype myself about a year ago (using RSS + TTS).

You might check out this startup: http://umanoapp.com/ which does almost exactly what you want. I don't know how the business model works exactly, but I would imagine that paying people to narrate would be fairly expensive.

You might also have a look at some of the stuff NPR is doing: http://www.npr.org/infiniteplayer/ http://www.npr.org/blogs/inside/2011/11/14/142303990/introdu... they are working on breaking the traditional radio show mold and queueing up individual stories based on personal recommendation.