It's basically the same strategy rperl uses, compiling a restricted and typed subset of perl5 to C++11 on the fly, via Inline::CPP http://rperl.org
I wouldn't call that JIT, because the term JIT is normally used for direct compilation to machine code, and all those other compile-to-c|c++-on-the-fly languages don't call it JIT neither.
I'm sure clicked the upvote, but your comment is gray now. :( Please, other readers, try to correct, upvoting the parent comment! It's a good comment, and it deserves to be upvoted. I can't do anything more. Thanks.
Edit: I've found the culprit: believe or not, the older Opera browser can have the "down" linked area in the middle of the up arrow! On the same hight (same Y) just changing the X position of the mouse will change between the UP and DOWN vote! The down vote area extends from the down arrow up to the top of the up arrow(!) and is of the same width (a few pixels at most). Weird. I must avoid that browser for HN.
I wouldn't call that JIT, because the term JIT is normally used for direct compilation to machine code, and all those other compile-to-c|c++-on-the-fly languages don't call it JIT neither.