BBN Technologies has come up a low-power mesh network as part of research funded by DARPA (Defense Advanced Research Projects Agency) to produce ad hoc wireless networks on battlefields.

The transfer rate is around the mbps (megabits per second) range and is fast enough to stream video, but only takes about a hundredth the power of a regular network. Consumer applications of this technology would be to produce more energy-efficient mobile devices. According to the article linked to above, it's unlikely that these mesh networks in particular would be used for anything like Municipal Wi-Fi.