Wikileaks - an uncensorable Wikipedia for untraceable mass document leaking and analysis - is an example of social software (wiki technology) being used for good governance.
"EUtube"™, the European Commission's new channel on YouTube, was officially launched on 29 June, 2007. EUtube is one new example of the use of the "Web 2.0" communication technologies at EU policy level.
The mission of YouthNoise is to inspire and empower young people everywhere to catapult their passion and idealism into movements to sustain the planet. This is achieved by encouraging young people to submit videos to this YouTube channel. See also the website at: http://www.youthnoise.com/
Here is a YouthNoise video about the obstacles that students in California face to getting a good education.
More on social software and social participation.