robert brewin, some sun guy, stated that parts of java will most likely be open-sourced within a year, possibly including the vm. that’s just nice!
http://www.infoworld.com/article/06/07/17/HNjavaopen_1.html
Personally I think it sucks. 
darkfrog
could you explain why?
i always thought, that it's bad to need a proprietary virtual machine to run a free java program. unfortunaly the free implementations of java never caught up with the development of sun's and probably never will. same thing with mono/dotgnu. so i think it will be great if the reference implementation is open-sourced, hopefully in a way that really makes it free software, allowing other free implementations to reuse sun's code. well, i doubt that sun will use a gpl-compatible license, they are really hooked on their own cddl, but it will still be good for free software in general.
There's nothing stopping anyone from creating their own fork on Java. The source has always been available and even though it wasn't open-source, there is no license restriction that keeps people from changing the existing code-base or adding to it in their own implementation. Besides, there are several implementations of Java (JRockit, Kaffe, GIJ, SableVM, etc). I prefer the control of the Java language be in the hands of the professionals at Sun. Even though I haven't agreed with many of their decisions I think they've done a very good job with Java. Honestly, I just think think Java becoming open-source is just going to add a bunch of bad code into the code-base.
The source may be available, but just looking at it could prevent you from writing your own implementation. Most of those forks you mentioned can't even call themselves "Java" because of the legal issues anyway.
Sun will keep some control on the JSR process, and I'm sure they'll keep their own build. They also use a lot of open source code already so your fears of bad code… well… ignorance is bliss? 
Opening the source will lead to more participation in bug fixing, something for which Sun could sure use some help. (Do I need to remind anyone of the two subsequent releases of the 1.4.1 VM that made it unusable with jME?). I hope it'll be under a pretty liberal license too, so you can copy some of the code they have into your own projects.
My only concern with this is the support issues. Requiring us to no longer say requires JDK1.5 but requires Sun Release JDK1.5 or compatible. Then we still get customer service calls complaining that software won't work on Apache JDK 12.0.1.2.
@darkforg:
yes, you can modify the java sources and use it in your own projects, but you may not redistribute it (or i misunderstood the license), which renders this practically useless. i still like it, because i can view the sources when javadoc isn't enough. the free implentations are naturally always behind sun's. many of them are moving towards 1.5 compliance while sun's 1.6 is on the way. a free sun implentation could close this gap.
i don't really fear forks. i just don't think it will happen. none of the big free software projects like netbeans, ooffice, the linux kernel, gcc, apache, eclispe… have produced a significant amount of forks, if any. sun will still be the driving force behind java and they will decide what goes into their distribution and this ditribution will be the defacto standard just like today. i doubt they will just set up a cvs with write access for anyone, so don't fear bad code.
@mojo:
ok, that could become a bigger problem than it is today, but i doubt it. even today people are using different jdks, which would/could become more compatible through opening java.
edit: you could also just say supported runtimes: sun, ibm, whatever, have good luck running it on a different one. just like many companies released games for win2k/xp which would run on win98 without problems, it's just not supported.
lets hope the open sourcing gets more people into developing a main sdk and not several smaller…
I tend to agree with darkfrog and MrCoder here, a lot of [incompatible] forks would definitely suck big time.
But as long as Sun keeps the "Mainstream Java" under its hood, we should be fine.
The greatest advantage will be seeing GCJ with full Swing support. 8)
Concerning the fear of incompatible VMs with jME:
I would not think too much about it. The best way to publish jME-Games is packing an own VM-Runtime anyway. If you do a commercial game those 20 MB won't count much on the CD/DVD. And for downloads, well, just provide two different versions. One with a runtime packed, the other one, without runtime for people who have the "Mainstream Java" installed allready.
Webstart is the only "insecure" part then. But as some on the board already noticed: Webstart is a challenge anyway.
Only thing I'm excited about is maybe multireturn may actually make it into Java now. 
I'm not trying to say that I think it will all just suck because it's open-source. I'm trying to say that a corporation maintaining a language has a lot of benefits over a community that just does it in their spare time. As we are all aware of Mojo and Renanse working for NCsoft I think we can all appreciate the benefits of getting contributions back from them more so now since it's not just a "in my spare time", but they are dedicated to working on jME and making is strong and stable. Granted a lot of their work doesn't get contributed back, but what does I'm sure has far more testing and thought than previously.