As Mike Chambers just announced on his blog, the new Apollo book that Mike, Jeff Swartz and I wrote is already up for preordering on Amazon.com. The tentative title is Apollo for Adobe Flex Developers Pocket Guide but that could change by the time it's published.
The book should come out at the same time as the public alpha for Apollo.
It's rare for an alpha release to be supported by published books, but we felt this release warranted it. Among other topics the book goes into some depth about Apollo's file access and HTML rendering capabilities. Mike has listed the table of contents in his blog post. He mentions that the book should also be available online shortly after the public alpha release date.