I've been working on my own system since 2001 called symetrism. Thinking I was the first to come up with the idea, I did a cursory search for open source governance and came across this site. I'm planning on launching symetrism.com (or some variance thereof) utilizing Joomla as opposed to media-wiki in the next 6 months. Unlike the meta-government project which seems to be a strong central government, I'm proposing a modular government. Here is the basic idea.
There would be different sectors to the government, each with their own "domain"
Sector 1 = local/municipal
Sector 2 = County
Sector 3 = state
Sector 4 = region
Sector 5 = Nation
Sector 6 = World
Each Sector would have a congress of 7 representatives. These representatives must posses an expertise in 1 of 7 fields (energy, environment, education, healthcare, economics, Child Welfare & Psycho-Social well-being). All citizens would have a direct vote on proposed issues. This will be facilitated through a closed network (seperate from the current internet) with terminals at "community centers". Voting will occur on a weekly basis, if the citizens failed to reach a 3/5 majority the issue would then be sent to the affected sectors congress. All issues will be classified by which issue (energy, environment, education, healthcare, economics, child-welfare & psycho-social well-being)they affect, Representatives may only vote on issues for which they are elected.
The Top Level Sector (TLS), currently sector 6 will hold dominion over basic human rights and conflicts between 2 or more nations. Each subsequent sector would have less general power but more direct power. For example at Sector 1, religious laws may be instituted except whereby they violate basic human rights.
There's a great deal more...if you'd like to see the initial ideas on old crappy geocities pages from 2001 look here:  and here  but keep in mind that A) the idea has evolved drastically after nearly 8 years of thought and B)they're horrible ugly websites, oh and C) you have to click the image to enter