Decentralized identity system, OpenID, appears to be the latest flavor of kool-aid permeating the Rails universe. OpenID makes it possible for users to identify themselves by using URLs that relate to a site where they have already logged in. Your application can then check this with the remote site and then use that status to tie that confirmed identity to their identity within your system. As much for my own reference as anything else, here are the main bits and pieces floating around regarding Rails and OpenID lately:

1) David Heinemeier Hansson started off by talking about how 37signals are looking at using OpenID.

2) Dan Webb wrote an excellent tutorial, "The No Shit Guide To Supporting OpenID In Your Applications", showing how to, well, use OpenID within Rails applications.

3) Ben Curtis demonstrates how to tie in OpenID with the popular Acts As Authenticated plugin.

4) The OpenID Authentication plugin wraps around the Ruby-OpenID gem and makes OpenID integration from Rails simple. Code examples are provided.

5) John Nunemaker points us to the Ruby on Rails wiki page for OpenID that provides links to several other resources.

6) Way back in the summer of 2006, EastMedia and Verisign developed a Rails-based open source OpenID server that was released under the Apache Heraldry project. Verisign use it to power their PIP system.

7) Dag Rorek Arneson built a Rails OpenID guestbook that's still available (but very slow) at http://rorek.org:3001/.

NEW! 8) Bernie Thompson has put together a kick ass page of Rails and OpenID resources as well as a screencast that quickly demonstrates the power of OpenID.