Kent Lagley writes on the Joyent blog about the work he has done with Dekel and Owen running GugaSpaces on the Joyet Accelerators. It's a well-written detailed blog and in a post entitled Cloud Computing with Java, Kent adds some more info on his personal blog, ProductionScale.
Some other exciting things about this exercise in the lab was that it was, in general, easy. We added and removed nodes, scaled linearly, pulled nodes out, re-deployed the application in seconds to minutes, we processed large amounts of data, and we did all this in the cloud with really minimal efforts.