There are posts all over the place about the Apollo Pocket Guide. But I want to offer my perspective now I've had a chance to read the sample chapter. The chapter looks at File operations using Apollo. Specifically it deals with the File and FileStream classes. The book is written in the clear and concise style we have come to expect from the O'Reilly pocket guides. They are straight to the point with clear examples to illustrate the application of the concepts discussed.
What was really exciting was to see some clear examples of how easy it will be to leverage Flex skills into Apollo development. The concepts for File operations were familiar from other languages (in my case PHP) and the methodology was familiar from Flex/AS3. This sample has really whetted my appetite for having a play with the Apollo alpha (which is apparently really close). Bring it on Adobe!