Yesterday, Apple released Java 2 Platform Standard Edition (J2SE) 5.0 Release 3. It's in Software Update, and you can read more about it (and find a download link) on Apple's About the Java 2 ... Release page. If you're like me, you might be slightly confused by the version number -- it seemingly jumps the Java version from 1.4.2 to 5.0, which is quite the move. In addition, unlike prior Java updates, this one doens't replace the 1.4.2 version; it's installed right next to it.
To help clarify the situation, macosxhints forum moderator hayne has put together a nice write-up that explains what's up with the version number, why two versions are installed, and how to put the new version to use.
Here's a summary of the topics he covers:
Mac OS X Hints
http://hints.macworld.com/article.php?story=2005111606295344