XMPP Case Studies
This page gathers link to various use cases of the XMPP protocol. Some of them are published by software vendors. They might be biased but give a good overview of what could be done with the XMPP protocol. It is up to the reader to keep its critisizing ability :)
The documents linked are PDF. Please do not submit press releases here, only case studies.
XMPP and VoIP
XMPP for Government
XMPP for Enterprise
This section cover cases of internal use of XMPP servers.