Hi,
I started a series of posts on using XMPP/Jabber from Ruby (and for me mostly from Rails) to my blog at http://devblog.famundo.com.
I just started, but I do plan to address a lot of things XMPP/Jabber can be used for.
Some of the special things that are almost not address in other sources, and will appear on the blog in the coming posts, are sending rich text messages, managing presence and sending messages to legacy IM systems (ICQ, AIM, MSN and YM).
So tune in if you are interested, and let me know if there are other parts of XMPP/Jabber you would like me to discuss and explain.
Bye,
Guy.