Wow!
I think Java is sufficiently entrenched at this point that it’s not going anywhere. There are almost certainly billions of lines of Java in the wild and these are not going to be rewritten in .NET. There’s also a vibrant community around languages like Clojure and Scala, which are both JVM-based. Certainly the existence of Mono has not killed Java, so I don’t see why this would either.
I think the more interesting thing is that Microsoft is actually moving the project over to Github, including using their issue tracker and such. This shows a big culture change. They used to feel the need to reinvent everything, such as making CodePlex instead of just using SourceForge.
I didn’t see what license this is under, only a hint that it’s OSI-approved.
-Eric