Here's a presentation by Google on their new 'Wave' protocol.
It's quite long at one hour twenty minutes but watching it is really the best way to understand what it's all about. Essentially it's a new way of communicating on the Internet that can do the job of email, message boards, blogs, IM and more.
The central idea is that conversation are held on a server as a 'wave', with users invited to join in who can then reply, edit start new sub-waves and invite other people all in real time - you see the updates from other people as they come in. Images can be dragged in and colaboratively edited. Formatting and spell checking happens on the fly.
Scripts called 'robots' act as invisible participants in these waves, turning URLs into clickable links, embedding videos and even real-time translation. You can create your own robots to do whatever you want.
Waves can be made more public or less private and - though not demonstrated in the presentation - there is the concept of groups.
Google's implementation uses HTML5 as their client. Waves can be embedded in other sites. Their example shows a blog and then comments. These comments can either be edited on their site or within the wave client with all updates showing up in real time wherever the changes are made. The server itself is open source and the protocol is open so developers are being encouraged to make their own wave implementations. Organisations will be able to install their own wave servers - it doesn't all go through Google themselves.
Wave servers can talk to each other - users on different wave servers can add each other to their waves.
This might very well be the next big thing, and for an application like Moodle the implications could be huge. It could do the job of the Moodle forums, messaging, blogs, wikis, filters (via robots) and be used for eportfolios and lots more.
It's early days - the software is (in Google style) in Beta and not available for general use. Personally, I think getting Moodle 'wave enabled' would have massive benefits.
Or it might all just be a flash in the pan, who knows.