Timothy B. Lee has a good survey of the current field of mesh networking at Ars. The good news is that it seems to be thriving outside of the labs where it originated. Better, the costs of deployment and operation seem especially conducive to use in developing countries. This is consistent with the highest profile mesh networking about which I know much of anything, the OLPC project.
The throughput pales compared to fiber of cable broadband but is directly comparable to what many folks use in developed nations in lieu of running cable throughout their homes, plain old WiFi. I was pleased to note among his examples mesh vendors working on municipal coverage.
There’s also an excellent section on open versus proprietary, noting that much of the systems out there may be open at the lower layers but are largely proprietary. The author definitely throughs his weight behind the need for open standards to aid competition and adoption.