I'm not a lawyer (and even Groklaw goes over my head most of the time), but it seems like this is the crux. If the lawsuit is based entirely around items that are open-sourced, then there's no lawsuit. But there's no real way to tell, since Oracle hasn't specified what exactly is being infringed.
And from a comment below:
>>Oracle wanted Java more open when it worked better for them, now it doesn't. They are allowed to change their minds, aren't they?
Yes, Oracle is perfectly welcome to change it's mind and say "We don't want this open source anymore." However, they can't (I believe) un-open-source things that have already been released. They can remove the license, take down the Java.com downloads, and continue developing Java under a proprietary license, but the whole point of OS is that the community could take their last OS release and fork it themselves.
This also means that a company can't open-source software or development tools, wait until they're implemented in various systems, then turn around and "un-open-source" them and sue for infringement.