While traveling the other day I was looking for some free wireless internet access, and when I looked in the Wireless/AirPort menu on my MacBook Pro I noticed the usual listing of publicly broadcasting wi-fi networks in the top part of the menu, but then under the "Devices" portion of the menu I noticed an entry labeled "Free Public WiFi". For a brief moment that sounded like what I needed, but then the alarms in my head went off, as it sounded more like a trap, something like the typical worm/virus/hacker/phishing setup.
I just took a little time to read up on it (here and here), and it appears to be a Microsoft Windows "feature". As the author of the second link states, it's "viral", but not a "virus".
In summary, if you're a Mac user and you see "Free Public WiFi" in your AirPort devices menu, just avoid it, it's not going to do you any good. And if you're a Windows user, you really want to avoid it, lest you catch the virus, er, get viral.