SFLAN is a free, cooperative WISP in San Francisco. It's not really a 'Community Network' because it has little or no community involvement, they provide free bandwidth and sell systems which allow people to connect to a WISP style distribution network which is then connected to the internet.
As of October 2007, in an ad-hoc test, only the following nodes responded to ping: sflan8.sflan.org sflan11.sflan.org sflan13.sflan.org sflan18.sflan.org