Pádraic Brady is in the midst of creating a book about the Zend framework. On its own, not huge news, but the way its being done is most interesting. It will be free to read, and new chapters will be added as they are written. Also each paragraph can be commented on. So think something is not clear or not correct, tell the author right there. Bruce Eckel has in the past done similar things with his ‘Thinking in …’ books, and he believes it makes for a better book.
The new zend framework book is called Surviving The Deep End, and can be found on its own site. 2 chapters are currently available