When I first started with BlackBerry development a few years ago it was difficult to find books on BlackBerry development. Since then interest has grown and today it is much easier to find good books on the subject.
I have just read one of the newer, BlackBerry Java Application Development: Beginner's Guide by Bill Foust. This is a useful book, even if you, like myself, is not a Beginner. It gives you a good overivew over the BlackBerry UI, which is probably what differs most from Java ME. It also has some material on more advanced subjects, like saving data and communicating over the network, which even though it uses the same classes and calls as standard Java ME is a bit more complicated.