The official Ruby library is on Github - https://github.com/openid/ruby-openid, but there have been no recent commits there. The last one was 2 years ago. It's the same story with Python and PHP.

Is anyone using these libraries? Are there any actively maintained alternatives?

Edit: I've posted the question on SO, if you prefer to answer there - http://stackoverflow.com/questions/9530904/whats-the-best-way-to-implement-an-openid-server-prererably-ruby