Actually there are two ham groups doing mesh in Berkeley - NALCO and everyone else. Most all the action is on the ham WiFI channel -2, though some standard channels are used. We are using AREDN software. NALCO is focused on emergency response and is a little protective with their mesh. I haven't had much chance to explore but one popular app seems to be "meshchat". I believe there are some 900 Mhz and 3 Ghz links as well.
I am using a NanoBridge M2 on a six foot mast on top of my roof to connect with Evans hall. It goes through a bit of foliage and is not strictly "line of sight". I am still able to get a good S/N dues the lack of interference.
Cheers - Martin W6MRR