JA Konrath's been writing a lot of terrific posts (with actual numbers!) on A Newbie's Guide to Publishing about e-books in general, as well as his own experience selling his books on Amazon for the Kindle. His latest post, Should E-books be Cheap? offers an in-depth examination of the possible future of publishing and e-books.
I don't have enough experience to know which of his predictions will be right or wrong (but I wish I was selling a hundred e-books a day like he is), but he's really got me thinking. Tornado Siren isn't available as an e-book yet, but I hope it is in the near future.