Two books from Syngress on mobile platforms security and forensics are to be on the market in June 2011.
One of them is focused on iOS security and forensic techniques and is authored by bobile forensic experts Andrew Hoog and Katie Strzempka.
The other one is solo work of Andrew Hoog. According to the draft outline published in viaForensics blog it will contain comprehensive review of Android platform, its security concepts and description of different android forensics techniques.

Good luck to the authors, keeping my fingers crossed everything to work well and the books to come out on time.