One of the things I did when I joined Yahoo was that I put all my Java books into boxes and took them out to the garage. Java wasn't my favorite language, but I didn't dislike it either. I can appreciate some of the advantages that it brought to the table and how it simplified some of the grunt work that is required when using another language.
Thus, it's been a few years since I really did anything serious with Java and I decided it's about time to refresh myself as well as finding out what all has been changed. The newer things I've been hearing are Spring and Hibernate while a lot of the things I was using before like Tomcat are still around.
I picked up the book, "Beginning Pojos" by Brian Sam-Bodden to give me an introduction on some of these topics. It's been a decent read so far. I think the next thing I study more on is GWT.