Google Wave is supposed to be one of the newest collaborative tools from the Google stable that will merge emails, social networking, IMs and wikis in a forum style room, using text and even video.
This tool is supposed to make sending messages and follow ups easier and more organized. While users can leave messages in response, and view and respond each time they log in, they can also view entries in real time. A wave will consist of blips which users can respond to.
Waves are slated to replace email once the technology is stabilized and becomes popular.
The preview version is now available to invitees and comes with 20 user invites/recommendations.
I have just started creating my list of contacts to test it out… looks good!