There are a couple TVWS (TV White Space) equipment designers now that I know of, from following discussions among the Wireless Internet Service Provider Association (WISPA) trade group in the US: http://www.carlsonwireless.com http://www.ktswireless.com/ http://spectrumbridge.com/

I believe the fastest airspeed I've seen claimed is 16 - 20Mbit/s using these devices. Although, this is using pretty basic 802.11-style signaling, and with a signal antenna. Multiples of this airspeed via dual adjacent channel modes, comparable to HT modes in 802.11n are technical possible, although likely unfeasible due to the licensing situation. Fortunately, the spatial multiplexing done right now with the fancier 802.11n radios is quite possible with TVWS, with the non-negligible drawback of then having to deploy 2 or 4 identical antennas at critical spacing b/w each other. (And these antennas are comparable in size to old UHF TV aerials.)

That said, deploying TVWS in an urban area doesn't make much sense right now. 10 to 20ml of range is quite nice, but the tradeoff is that you will either have to severely limit your subscriber density, or severely reduce the bandwidth allotted to each subscriber.