Seems like everyone is in the middle of Martin Fowler's Patterns of Enterprise Application Architecture.  Of course, that's expected, both when Martin has something to say, but also when any new Patterns book is written. 

At my company, we've even started a weekly lunch study group to discuss the book, and also to introduce Patterns to the uninitiated.  Seems that the concept of design patterns don't always enter the mind of the average programmer when they think of good design and opportunity for reuse.  Fortunately there are lots of resources for the beginner.  My favorite is the Portland Pattern Repository.