Teledesic is a non-geostationary fixed satellite service, so handheld mobile service will not be available. Teledesic's laptop-size terminals are fixed, although it will be possible to transport them. The Teledesic Network also can support aviation and maritime
applications because they have direct line-of-sight with the satellite network.
IMHO, I think it is too early to analyze the competition between Teldesic and Gilat. However, it is important to note that Teledesic is deploying and maintaining a satellite network. Gilat is an equipment and service provider on the ground. Gilat could thus potentially build ground based equipment for the Teledesic system. Also, Teledesic seems more focused on the consumer market, while presently Gilat sells to businesses/organizations/government.