If you're interested in using ZooKeeper but not with C or Java, here's something for you. I've written a Ruby extension wrapping the ZooKeeper C client library. It wraps the get, set, create, delete and getChildren methods, and implements one of the locking recipes. Details over on the github page.
It's open source, released under the MIT license. Share and enjoy!
Note: of course, it's not very mature yet. Expect many warnings about threading-related stuff, and possible instability. Help is welcome to get its threading playing nicely with Ruby -- just drop me a line, or sign up on github, fork it, hack, and send me a pull request!