There's a plan to do some work on it (including trying to port it to 64 bit) this summer.
I think it's 64-bit (?). Most of the time it hasn't mattered for me, at least when writing scripts.
You can also just build the "old" version (0.6.7) with the `-m32` GCC flag, and it works fine on 64-bit Linux and OS X. It's very stable in my experience, and works fine.