Designer Jon Hicks (famous for things like creating the Firefox icon via Fireworks) has written The Icon Handbook:

I’ve set out to create the manual, reference guide and coffee table book that I always desired… Along the way, I talk to icon designers such as Susan Kare, David Lanham and Gedeon Maheux of the Iconfactory and many more about their process behind well known icons.

The book promises to get into technical details, too, as in this excerpt about using fonts in lieu of bitmaps to present icons. I can’t wait to get a copy.