Eclipse3.1.2/Equinox is also the core of the WebSphere Application Server 6.1
I've written a lot on this for IBM magazines and a RedBook (to be published soon), but Eclipse 3.1.2 / Equinox / OSGI is also the core of WAS, and provides benefit to its architecture. Check out the plugin and configuration directories, and the OSGI console shell script in the bin directory...