ComputerWorld has a FAQ to why an open-source Java would be good for software development. Considering Java is considered the most popular programming language among developers such a move by Sun would be welcomed news.

What's the big deal? Isn't the source code for Java already available? Yes, the source code for Java has been available for years via the SCSL and JRL license programs, but a true open-source release would make it possible for developers to innovate more freely with Java, with less involvement from Sun and fewer licensing restrictions on distribution. Sun, while making periodic noises about the possibility of open-sourcing Java, has resisted this move, until now. More at ComputerWorld.com

By the way, open-source fans may be interested to hear that PHP is ranked the fourth most popular programming language (with C and C++ ranked second and third). See the TIOBE Programming Community Index for additional listings of program languages ranked by popularity.