Google's ultra-fast broadband network in Kansas City, Kan., is a magnet for technology entrepreneurs, who since September have been turning a section of the city's antiques district into a "startup village." Experts say the transition reflects a wider trend in the tech sector, as firms seeking room to grow broaden their horizons beyond Seattle, San Francisco and Boston and flock to places such as Omaha, Neb., and Des Moines, Iowa.