According to their website:
ScatterChat is a HACKTIVIST WEAPON designed to allow non-technical human rights activists and political dissidents to communicate securely and anonymously while operating in hostile territory. It is also useful in corporate settings, or in other situations where privacy is desired.
So basically, it's a hacked-and-modified version of the Gaim Instant Messaging client, that comes with a number of interesting security features, including the ability to talk to the EFF's Tor network built-in. Point-to-point encryption and transmission anonymity has been available in various forms before, but only in a number of different independent packages, plugins, and proxies. ScatterChat is designed to be secure out-of-the-box, and easy to set up for even the technological novice, without any extra effort needed to configure and enable those essential encryption and anonymity features.
Easily available and easily usable privacy like this is a good thing for everyone. Check it out, and spread the word. There are obviously other ways, but the more people using the likes of Tor, OTR, and other privacy technologies, the better.
Source code and a Windows installer are currently available, as well as an ISO of the discs distributed at HOPE. Linux binaries and a Fink package for OS X are in the works.
This project also has a freshmeat page, and a Slashdot thread.