Idavoll is an implementation of a generic publish-subscribe service component for Jabber servers, as described in JEP-0060
Secure video calls, conferencing, chat, desktop sharing, file transfer, support for your favorite OS, and IM network. All this, and more, in Jitsi - the most complete and advanced open source communicator.
Jabber/XMPP support in MoinMoin
Nounours is a Javascript Web client to Jabber protocol. It's using BOSH implementation to communicate with a jabber server.
Prosody is an exciting new server for Jabber/XMPP written in Lua. It aims to be easy to use, and light on resources. For developers it aims to give a flexible system on which to rapidly develop added functionality, or prototype new protocols.