Mapping your Move to the Windows Azure Platform
The Windows Azure Handbook, Volume 1 by David Pallmann has just been published. It is the most up-to-date work on Windows Azure that I have seen so far. It is available in print or you can get it as an eBook at Amazon.com.
Volume 1 is on Planning and Strategy. Subsequent volumes will cover Architecture, Development and Management.
This is an excellent book for anyone evaluating and planning for Windows Azure. It also provides an excellent comparisons of several other public cloud services including Amazon Web Services and Google AppEngine.
One of its strengths is detailed documentation of a complete methodology for evaluating the technical and business reasons for determining which of your applications should be moved to the cloud first.