Google Wave

Google Waveis "a web based service, computing platform, and communication protocol designed to merge e-mail, instant messaging, wikis, and social networking." (Wikipedia). Google Wave is currently in beta, and can only be used by the approximately 1 million people who received beta invitations. Google considers current versions of email to be outdated "Snail mail." Google Wave is incorporating more recent technologies. It is "what email would look like if it were invented today" (Google Blog).

Google Wave transmits messages in real time. With IMing and Facebook, a message will not appear until the person typing it presses enter, so you spend half your time waiting for someone to send their response. Transmitting in real time allows the users to read messages as they are being typed, cutting down on reply time drastically.

This video from the developers at Google presents an overview of Google Wave in under 10 minutes.