Models for a civic commons

Over the past couple of weeks I've heard at least five different possible models for an online civic commons mentioned at various meetings about online communities and e-democracy, and I think we need somewhere to talk about them. Here's the models - and I'm sure there are more:
* A Government-supported Civic Commons in Cyberspace, advocated by Jay Blumler and Stephen Coleman
* The BBC iCAN! site for campaigns and discussion
* An online market for trading time-based service
* A commercial model like UpMyStreet conversations
* A site that would aggregate discussions taking place in online civic networks - an idea floated at yesterday's meeting on grassroots and networks

There are advantages and disadvantages in each, I suspect.
A Government-supported site could be a place for institutional democracy to meet grassroots interests - but would it be moderated with a light touch, and would people feel comfortable there?
The BBC site is great, comes from a still-trusted stable, but offers so much information I find it a bit difficult to get to the conversations
As I wrote here, I don't think markets are the appropriate model for civic discourse - though supporters argue it could be a way to volunteer.
A commercial model might be lively, but financially vulnerable
Aggregating existing networks would not be as tidy as iCAN!, but would really harness the energy of grassroots enthusiasts, leaving them with ownership of the content. I first heard about the possibilities of this from Lee Bryant of Headshift, and expect to see more examples soon.
What we need, of course, is an online place to discuss the model for a civic commons....anyone volunteering?