Scott Ambler (see earlier posting) recommended this soon-to-be-published book by Addison-Wesley.
Joshua Kerievsky bridges the gap between the practice of refactoring and the art of designing with patterns. The heart of the book is a catalog of 27 refactorings that covers such areas as creation, generalization, simplification, protection and accumulation. The real-world examples in this book illustrate when it makes sense to refactor to a pattern and how low-level refactorings are combined to implement patterns.