[Dev-luatex] LuaJIT?

Hi guys, has anyone luatex working with luajit? so far i've only managed to get to compile a 32bit version under ubuntu 64 bit - /luajit hasn't been ported to a 64 bit yet/. Currently the interpreter works. here's the difference in speed between standard lua and the jit version; http://shootout.alioth.debian.org/u32q/benchmark.php?test=all&lang=all&box=1, and generally; http://shootout.alioth.debian.org/. In summary; I'd just like to know how much roughly how much effort is required and If anyone has looked into it. Mohamed