Many people are probably wondering why there are so many alerting them for invites to Google Wave or celebrating that they finally have a Wave account. More are hankering for invites.
Here is a great guide on getting started on Google Wave. Essentially, it's the next generation e-mail that's not quite e-mail, and live chat that's not quite just chat. It's e-mail people can edit in real time, attach videos to, and only one copy gets retained. I have yet to really explore all it can offer and once the Almighty Google has fixed all its bugs, they say that it will make Facebook and Plurk and Twitter obsolete.