The JSR-270/J2SE 6 ("Mustang") Release Contents have recently been submitted to the JCP by Sun and is up for Review Ballot.
"The proposed specification will define the feature set for the next major release of the Java 2 Standard Edition platform, code named "Mustang", which is targeted to ship in 2006. Mustang is one of a ongoing series of J2SE feature releases. The goal is to ship feature releases on a regular 18-24 month cycle, with each release including a combination of quality improvements and new features. This JSR will not itself define any new features or enhancements; it will, rather, enumerate features and enhancements defined in other JSRs or through the JCP maintenance process."