If you're walking around downtown Seattle, look up: You'll see off-white boxes, each one about a foot tall with vertical antennae, attached to utility poles. If you're walking around downtown while looking at a smartphone, you will probably see at least one—and more likely two or three—Wi-Fi networks named after intersections: "4th&Seneca," "4th&Union," "4th&University," and so on. That is how you can see the Seattle Police Department's new wireless mesh network, bought from a California-based company called Aruba Networks, whose clients include the Department of Defense, school districts in Canada, oil-mining interests in China, and telecommunications companies in Saudi Arabia.