Google Wave is an online tool for real-time communication and collaboration. A wave can be both a conversation
and a document where people can discuss and work together using richly formatted text, photos, videos, maps, and more.
What is a wave?
A wave is equal parts conversation and document. People can communicate and work together with richly formatted text, photos, videos, maps, and more.
A wave is shared. Any participant can reply anywhere in the message, edit the content and add participants at any point in the process. Then playback lets anyone rewind the wave to see who said what and when.
A wave is live. With live transmission as you type, participants on a wave can have faster conversations, see edits and interact with extensions in real-time.
Some key technologies in Google WaveReal-time collaboration
Concurrency control technology lets all people on a wave edit rich media at the same time.
Natural language tools
Server-based models provide contextual suggestions and spelling correction.
Extending Google Wave
Embed waves in other sites or add live social gadgets
Source : http://wave.google.com