YOU may already have seen them or read about them in the press. If not you soon will. Mysterious chalk marks appearing on pavements around the world show where there are Wi-Fi wireless Internet nodes that anyone with a portable computer can use to surf the Web at someone else’s expense.
The idea behind the marks dates back 70 years to the Depression, when hobos in America developed a secret code to tell each other which houses were friendly and offered food and shelter, and which would let the dogs loose. They called it “warchalking” and the new marks are…
