I've noticed that Sun did quite a good job updating the Java Tutorial's website. I read a couple of tutorials on this website before but I didn't find it very good, or at least the tutorials I read weren't. Lately I've been hitting this site quite often while researching various Java issues and I've noticed that the content has improved quite a bit.
The update seems to have a lot to do with upcoming release of JDK6, because the content already reflects the new features included in this release. Either way, it is nice to have one place to go to get some more insight into Java core libraries and tools and the proper way of using them. Some parts of the tutorials I've checked out were a little bit too "high-level", but that is understandable considering the scope of JDK. The only critisizm I have about the site is that it could use some "face lifting", but that might change by the time JDK6 is released.