XMPP Roundup: services
Facebook Chat on XMPP
By an ex-Googler https://imo.im/
http://livefyre.com/ for cross-domain, cross-blog commenting in real time over XMPP.
After Facebook, Vkontakte
The Russian Vkontakte social network is using XMPP as the basis of their chat system, enabling third party clients to connect.