Perl does a kind of half JIT when you start a script. It doesn't compile fully down to native machine code, but it does parse and lex the script to build an internal representation. The code is then interpreted, but since it doesn't have to parse each line again it runs very fast and also you can interpret code on the fly in a variable so you get the best of both worlds.
This has been the usual way to implement interpreted languages for decades; Perl isn't special in that regard. JIT generally refers to generation and execution of native code specifically.
