Wow, i didn't see this comming. It'll be interesting to see what kind of license they come up with for it. Hopefully they allow it to be developed as a community process like other open source projects. Obviously they'll have obsesive control over it at first but there are many out there that could do great things contributing to java if they had the oportunity.
http://www.vnunet.com/vnunet/news/2156205/sun-promises-open-source-java