It's not (yet) publicly available. But Sun is planning to make it Open Source,
but my understanding is that this won't happen before January.

???? wrote on 18.11.2006 09:31:

1.5: http://tiger.dev.java.net/
1.6: http://jdk6.dev.java.net/ (formerly mustang)
1.7: http://jdk7.dev.java.net/ (formerly dolpin)

IIRC, it's a click through for use under JRL (Research) or JIUL
(Internal Use) licenses.

There are other implementations. For instance, Apache has an
incomplete[1] 1.5 implementation in development, available under the
Apache license:

http://harmony.apache.org/downloads.html

Tom Hawtin

[1] http://www.kaffe.org/~stuart/japi/htmlout/h-jdk15-harmony.html