Jython Books
1. Jython Essentials. Samuele Pedroni, Noel Rappin. O'Reilly and Associates. 2002.
2."Jython for Java Programmers." Robert Bill. New Riders. 2001.
3. Python Programming with the Java Class Libraries: A Tutorial for Building Web and Enterprise Applications. Richard Hightower. Addison-Wesley Publishing. 2002.
4. An Introduction to Computing and Programming in Python: A Multimedia Approach. Mark Guzdial. Prentice Hall. 2004.
Books 2 and 3 are available from Safari.
For a detailed list of books and articles look at:
Ed Taekema has compiled a fine list: Jython Bibliography
Building an Application Web Service based on Jython Scripts
Jython Tutorials
1. First and second part of a very good tutorial written by Barry Feigenbaum, IBM (download needs registration).
Other Resources
In the back of Learning Python is a very cool Jython graphing example.