Read up on Jtrix, an open source (LGPL) distributed app framework that's just been announced. They say:
[Jtrix is] for developing applications which smoothly evolve and adapt. That means they are scalable, adaptive and cost effective to run.
It reminds me of my master's work on Hive, a Java framework that includes some sort of discovery mechanism, remote messaging, mobile code, all with an interesting bottom up design. The engineering work on Jtrix looks solid - lots of tests, good documentation. The introduction for everyone (PDF, 29 pages) is the first thing to read if you want depth.
The thing I'm curious is how they make a business case for doing this kind of work - I'd love to have an answer for that for myself. There's a bit about this in the FAQ, but it's not very specific ("we wanted it"). Their parent company, Hyperlink, seems to be an incubator of sorts, but with not much info about their seven years of incubating. Regardless, Jtrix is out there, and it's free, and das ist gut so.