Brian Fling's book, Mobile Design & Development, published by O'Reilly in 2009, is available to read in its entirety online. Fling says he says 75-80% of the content of the book (which is some 68,000 words) is up to date and extremely relevant as of March 2011.
More from the author:
I wrote this book to have something for everyone interested in designing in developing for mobile devices, regardless of experience and regardless of the application. The first half is a crash course in the mobile ecosystem: how to develop a strategy, address the mobile context—even how to decide which of the multiple mobile application types is best for you, and finally, how to create a user experience for it. The second half is focused on using these principles to make a mobile website or web app.
This means this book isn't for anyone looking for a quick fix to the “mobile problem.” As I told my excellent editorial team throughout the writing process, “this is a book that teaches people how to cook, not a collection of recipes.” However being O'Reilly's first book on mobile, we decided to cover a lot of ground, basically detailing mobile from it's origins to the devices of tomorrow.
Read at the book site.