Essentially, a Wave is a collaborative entity that is hosted online with a set of participants who interact with it. It's very general and can be used in an e-mailish way, a document editing way, an instant messaging way, etc. There are all kinds of extension possibilities as well, and surely there will be tons of applications for this that no one has thought of yet.
The demo is long but impressive. Some of the things I liked:
- Messages can be transmitted character by character as they are typed, so instant messaging is more interactive
- Robots (software controlled wave participants) can be built to perform any of the tasks that humans can do. They can edit the wave contents for things like spell checking and language translation.
- All of the changes made to the wave are stored with a history, so you can playback this sequence of changes as a video to see how a wave evolved.