When the door is always open

NOT long ago, at the height of the dotcom boom, you could chart the rise and fall of companies by looking at the garish artwork sprayed on the walls of loft buildings in San Francisco's Multimedia Gulch district. But now, thanks to wireless technology, there is a better way. Driving around the city on a warm night a few weeks ago, Bill Cockayne, a Silicon Valley veteran, opens his car's sunroof. His friend Nathan Schmidt posts what looks like a small fluorescent tube through the open roof and plugs it into a laptop computer. “Metro/Risk”, says the computer in a clipped female voice as the car makes its way through North Beach. “Admin network. BCG.” Then a robotic male voice booms out: “Microsoft WLAN. Archangel. Whistler. Rongi.”