In 2009 I competed with several of my classmates from SE2011 in the ICFP contest. By 'competed' I should clarify that all I did was write the VM. The rest of the team actually did the problem-solving goo.
I wrote both of the VMs we ended up using, the first being a relatively slow naive imeplementation of the spec, and the second being a JIT-compiling VM that ran each program in about 10% of the time the original version did.
I found this code laying around my home directory, and figured that it should be remembered somewhere, so here it is. I would have included the original non-JIT VM as well, but the snapshot of the SVN repo that I have is a heavily hacked-upon version, and the repo that held the history is long since gone (go SVN!).
Because it's hideous.
orbit_vm_jit uses libjit, which is exactly what a library should look like. It seems that it's no longer maintained, which makes me sad.