GigaOM writes, At the Defcon hacker convention going on now in Las Vegas, roughly 650 attendees received a custom phone that allows them onto a secret local cell network called NinjaTel. Both Ars Technica and The Verge have stories offering screen shots and details, but I’m curious about the real world implications of this experiement. Ars Technica says the network uses both a GSM network (not sure what frequency it’s operating in, or if it is indeed a real “pirate” network as The Verge asserts) and secured portions of the conference Wi-Fi : For redundancy and reliability, Ninja...