I haven't seen this appear on Planet Eclipse yet, but Bug Labs is developing BUG. They call it "an open source, web-enabled, modular software + hardware platform".
It looks like a set of hardware modules that you can combine into a single device. All modules interconnect and can be programmed in Java. Apparently their software stack is based on OSGi and their SDK runs on top of the Eclipse SDK. Check out the screenshots at the bottom of the products page.
Looks really cool.