Google Wave
Google Wave is a product that helps users communicate and collaborate on the web. A “wave” is equal parts conversation and document, where users can almost instantly communicate and work together with richly formatted text, photos, videos, maps, and more. Google Wave is also a platform with a rich set of open APIs that allow developers to embed waves in other web services and to build extensions that work inside waves.
http://wave.google.com/
http://code.google.com/apis/wave/
http://www.waveprotocol.org/