I have moved my more complex scripting from Perl/PHP/Python to Lua for a lot of reasons. One being that Lua (even PUC Lua) is a good deal faster than Python (or /bin/sh); another is that, if I want even more speed, I can use LuaJIT (which keeps me stuck at Lua 5.1, but Lua 5.1 is perfect for my needs).

I wish Lua 5.1 could become part of POSIX; there are a lot of implementations of it out there.