At the Google I/O developer conference, Lars Rasmussen announced that Google Wave no longer requires invitation. If you have a Google account, go to wave.google.com and you can use Google's real-time communication service.
Google Wave is now available in Google Apps, so that businesses, universities and other organizations can improve communication flow.
"Anyone on a wave can edit or reply to any section, keeping discussion in context with relevant content. Everyone's typing shows up instantly, and Google Wave lets new participants get up to speed quickly with organized discussions and playback to see how a wave evolved."
Google Wave really shines at Google I/O, where it's used to view live notes, ask questions and discuss sessions. Here's a wave for today's keynote.