Yes, the name Mustang is no more… Java 6 is now official.. What’s in it?

Easy-to-use APIs for Web-service clients. You can read more here: http://java.sun.com/developer/technicalArticles/J2SE/jax_ws_2/.

You can mix scripting languages into your code and JavaScript comes with the distribution. Also Java 6 can be expanded to add other languages (Perl seems like an obvious choice – hopefully someone will work on that if it’s not being worked on already): http://java.sun.com/developer/technicalArticles/J2SE/Desktop/scripting/

JDBC 4.0 Support and an all-Java JDBC database included in the JDK. It’s Apache Derby (aka IBM Cloudscape) and is considered a fairly decent desktop database (especially given it’s pricetag): http://developers.sun.com/prodtech/javadb/

Swing continues to become more robust with new Desktop APIs (Swingworker, JTable sorting and filtering, GroupLayout just to name a few):
http://java.sun.com/developer/technicalArticles/J2SE/Desktop/javase6/index.html
Here’s some screenshots of the new Swing Desktop in action: http://www.ensode.net/java_swing_mustang_screenshots_gtk.html

Monitoring and Management APIs with tools that attach on demand:
http://blogs.sun.com/dannycoward/entry/crash_course_java_se_monitoring

And the new JConsole is sweet looking too:

There’s way more, too! This release is a huge step foward and you can download it here : http://java.sun.com/javase/