Like https://github.com/kenpratt/wikipedia-client ?

There are a couple of implementations for Ruby--but I haven't been able to get them to work.

So, I wrote one that was dead simple, but have only implemented the API features I needed, which is mostly related to deleting things, as I use it for mass spam deletion. If you're interested, I'll upload it somewhere, but like I said, it's very incomplete.

Here's mine: https://github.com/jpatokal/mediawiki-gateway