That is so wild. It's like the ad-hoc wifi equivalent of a chain letter.
Edit: Thinking about it, it's even crazier... Because the bug only happens when there aren't any available networks, it springs up in situations when there are a lot of people looking for wireless, but there isn't any— on buses, conferences, etc. The exact sort of situations where people are most likely to try out "Free Public WiFi", so the virus is more likely to propagate.
Furthermore, the name is important. In order for it to become a widespread phenomenon, it has to be a name a lot of people will click on. But we can imagine that a lot of people have set up ad-hoc networks with different names that wound up being temporarily duplicated by the bug. Some of those with attractive names may have caused further duplication before finally disappearing. The more attractive the name, the more likely it is to be duplicated before being overwritten. In effect, the name "Free Public WiFi" has been selected for.
I'm calling it: This is the first (global?) distributed wireless network that evolved on its own. Unfortunately, evolution doesn't require that it actually be useful to people :P