I was listening to a podcast and there was an ad for Murder at Avedon Hill, a fantasy/mystery novel that's being serialized as a podcast (warning: this isn't literary fiction but rather more D&D fantasy as it was originally planned as a tournament module for the Neverwinter Nights video game).
In many ways, I think the podcasts "piecemeal" mode sets it apart from say, audiobooks. Whereas you buy one whole package in the latter, podcasting lets you distribute your book chapter by chapter on a regular basis.
Lately, I haven't really read much of serial novels. The last popular serial novel I think was Stephen King's The Green Mile. Anyway, between online publishing, print-on-demand, and podcasts, we might be seeing the rebirth of the serial novel.