Technical Info on the NTL Wireless TrialOgier Electronics appear to be the company behind the trial. There website has a wealth of information for those considering the service.
The antenna appears to be around 30cm by 30cm and fairly square and with a 10km diameter of coverage from the main transmitter which will support upto 16000 users, to get around line of sight issues repeaters can be used, i.e. if a tower block imposed a large dead spot they have ways around it. The repeaters can also be used to improve the range of the service as well. Also a very useful option with flats is that multiple users can share the same wireless module, each user just gets there own cable modem.
No specific claims are made regarding the latency of the service but it does mention gaming on the internet and shows a driving game.