The Farstream (formerly Farsight) project is an effort to create a framework to deal with all known audio/video conferencing protocols. On one side it offers a generic API that makes it possible to write plugins for different streaming protocols, on the other side it offers an API for clients to use those plugins. The main target clients for Farstream are Instant Messaging applications. These applications should be able to use Farstream for all their Audio/Video conferencing needs without having to worry about any of the lower level streaming and NAT traversal issues.
WWW: http://www.freedesktop.org/wiki/Software/Farstream