[actsasbuffoon]

Ruby is also usable, as are a few other languages. Unfortunately you need to compile Vim with support for a given language if I recall correctly. VimScript is the only extension language available to all versions of Vim, so that's a consideration if you intend to share your creations.

That said, it's possible that a large percentage of people use a Vim binary with Python/Ruby/etc. support. I have no idea what the usage statistics are.

[aaronem]

The impression I had was that Python had become a de facto standard Vim extension language, but evidently that's very much not the case. Definitely a drawback; it's nice in the short term, perhaps, to be able to choose your favorite among various scripting languages, and use that to extend your editor, but in the long term it seems likely to result in a lot of fragmentation.