There is not much literature in the area of mobile user interface design. This book is not written completely by Christian Lindholm and Turkka Keinonen, though; this book has several authors from Nokia.
It is an exciting and good-looking book on the history and background of the extremely successful Nokia mobile phone design. It is very down-to-earth and visionary at the same time.
If you work in the area of user interface design for mobile devices, this is a must-read. There are many new ideas in this book and I learnt much from it.