Google announced a new service coming later this year called Wave. So far I haven’t played with it and all I know is what they told people at Google I/O when they unveiled the developer preview.
The open source project will be a new way of communicating with the best of email, IM, blogs and all other ways of communicating on the web.
I have signed up to be notified when they are ready to let more people in and I will be reviewing it shortly after I get in.