The Mozart Programming System is an open source implementation of the programming language Oz 3.
Oz is a multi-paradigm language that supports declarative programming, object-oriented programming, constraint programming, concurrency and distributed programming as part of a coherent whole.
Congrats! Just downloaded the binary (alpha.0+build.37.830c8a4) and all the basics seem to work on Ubuntu 12.04. Obviously loads to do still, so I've joined up!