Google Wave, according to Google, is an online communication and collaboration tool where where people can discuss and work together through text, photos, videos, and more. It's basically a protocol designed to combine social networking (facebook!), online forums, emails, IMs, wikis and the like. It is even predicted that people or the millions of web surfers would just be content to "ride the wave". Key technologies of the Wave include Natural language processors, Real-time collaboration and it could add live social gadgets.
Initially, 100,000 users were given the chance to use it and each of them were allowed to invite up to eight more users. If you're lucky, then you must have the controversial Wave account (Apparently, I'm not that lucky T_T). Even hundreds are willing to pay just to have the account.