Jitsi seems to be a lot of things, from an IM Client agglomerator such as Pidgin or Digsby, a combined XMPP and SIP VoIP client to a videoconferencing hub with all traffic encrypted using ZRTP.  This Open Source software also claims integration with Microsoft Outlook and Apple Address Book, putting it in competition with Skype on more than one front.  Unfortunately it will not connect to all online SIP or XMPP provider but Jitsi does offer an open XMPP bridge to host video calls and as it is open source there is no reason you could not construct your own.  With the release of version 2.0 a host of new features and improvements have been added which you can read about by following the links at Slashdot.  They have also partnered with the FMJ Project to allow recording of sessions as well as other possible customization thanks to the developers Wiki.

"Among the most prominent new features people will find quality multi-party video conferences for XMPP, audio device hot-plugging, support for Outlook presence and calls, an overhauled user interface and support for the Opus and VP8 audio/video codec. Jitsi has lately shaped into one of the more viable open Skype Alternatives with features such as end-to-end ZRTP encryption for audio and video calls. The 2.0 version has been in the works for almost a year now, so this is an important step for the project."

Here is some more Tech News from around the web:

Tech Talk