Once you grok Lisp, everything else is easy. You come to realize that the vast majority of what passes for "new technologies" is really just a re-discovery of something that exists (or is easily implemented) in CL. That makes it a lot easier (if a tad frustrating at times) to keep up.
EDIT: CLOS, and generic functions in particular, are a HUGE lever that no other language has co-opted yet.