I just received word that James Murty's new book, Programming Amazon Web Services, has been published and that copies are now available. The Amazon site is still showing the book as available for pre-order but this should change within a day or two.
The book contained detailed information about the use of Amazon S3, Amazon EC2, Amazon SimpleDB, Amazon SQS, and the Flexible Payments Service. I've reviewed several drafts of the book; James has done a really good job of collecting and organizing the information that will allow you to make good use of each service.
In the space of 13 chapters and 2 appendices, James details each service -- what it is, what it does, how it fits in to the other services, and how to use it to solve real problems. There's plenty of Python and Ruby code too.