EJB Design Patterns (published March 2002)
ecx.images-amazon.com
ISBN 0471208310
Consists of 20 EJB-specific patterns written a style similar to Alexandrian Form. The book is 'lower level' than most patterns books, in that it is intented to cover EJB-specific implementation and design issues.
The book also contains:
A chapter on going from requirements to patterns-driven design
A Chapter on Build-system and Junit testing strategies (contributed by Randy Stafford)
A chapter on how to use Java Data Objects with EJB as a best practice
The book will be available on The Server Side as a free downloadable PDF here:
www.theserverside.com 
Amazon Link
www.amazon.com
Available online at: www.theserverside.com
Although you do have to be a member of The Server Side to download it.
This isn't so much a book of Design Patterns as idioms and best practices. Much of the material is concerned with architectural principles and workarounds to bugs rather than describing patterns. The Rule Of Three isn't really adhered to, largely because it's hard to find examples of enterprise applications with available source code, which makes the entire book seem very theoretical. Fowler's Patterns Of Enterprise Application Architecture suffers from the same problem.
See original on c2.com