Matt and co. at Automattic released Prologue, a WordPress theme (GPLv2) which creates a twitter-like experience based on posts to a WordPress blog. (It’s already been updated once).

Check out the Prologue Demo Blog for a sense of how the theme works. This could easily be used to create a kind of workgroup twitter, and given the number of different plugins / mechanisms for creating a blog post it could be extended to mobile, IM, and other integration points. The important difference, of course, is that you’d be hosting your own experience, not relying on Twitter – though that also means you’d need to build your own audience.

The folks at SixApart released the Activity Streams plugin for Movable Type which

lets you aggregate, control, and share your actions around the web as well as a list of your profiles on various services. With the Action Streams plugin you keep control over the record of your actions on the web. And of course, you also have full control over showing and hiding each of your actions. The Action Streams plugin, by default, also publishes your stream using Atom and the Microformat hAtom so that your actions aren’t trapped in any one service.

You can see a great example of this on David Recordon‘s site (he’s the Open Platform Lead for SixApart) and in a group context on the Movable Type Activity Stream page.

Both of these represent significant advances toward an open source, open standards, portable data approach to social networking and lifestreaming.

Since the implementations are open source, expect similar functionality to be ported across platforms.