Atomatrix
Multithreaded execution system of atomic matrices with dynamic compiler, a network environment, and an object-oriented OS. Open source, BSD.
http://atomatrix.sourceforge.net/
Iguana Project
Investigating use of object-orientation, computational reflection, and metaobject protocols (MOPs) to support dynamic customizing of (system) software.
http://www.dsg.cs.tcd.ie/~coyote/