XMPP4R is an XMPP/Jabber library for Ruby.

Features:
* Fully object-oriented (well, it's Ruby ;)
* Aims at being XMPP compliant
* Threaded and non-threaded mode
* Well unit-tested and documented code
* Uses well-known and well-tested software like REXML
* Very easy to extend
* Released under Ruby's license, which is compatible with the GNU GPL

WWW: http://home.gna.org/xmpp4r/