You can read more about Matthew's journey at
http://www.passarella.com/matthew.htm and
http://www.passarella.com/matt2.htm - my family also started an annual walkathon to raise money for pediatric brain tumor research,
http://www.matthewsmiles.org -- I recall that I put my nose to the grindstone to finish SHIMMER (first draft) before Matthew began his radiation therapy. I had a similar nose/grindstone experience finishing Wither's Rain.
WITHER on Kindle/eBook: my earlier novels are owned by Pocket Books, all rights, foreign, audio, eBook, etc.. I can't offer them in eBook fomrats, only Pocket Books can. The newer ones seem to have been released on Kindle. Some of the older ones are available in other eBook formats. You can find some of those on simonsays.com (Simon & Schuster Website), but I'm not sure if Wither is among them. Sorry I don't have a better answer. I'm kind of at their mercy for any additional rights usage.
-John Passarella
http://www.passarella.com