That's a very nice example. I just wanted to leave a URL to related work in the Sun's JVM Hot Swap mechanism.

http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4910812

This (more in the PDF available through there) shows that the JVM already supports some of the desired features and people are considering the inclusion of more.

(bah, can't think straight right now, so see! no bashing :-) )