Flutterby™! : Open WiFi

When I click on the little network icon on my Ubuntu laptop, some of the wireless networks listed have little icons next to them indicating that they're locked, some don't, indicating that they're opened. I have wondered why not replace that icon with a little clock symbol, indicating how long it'd take to break the encryption? That way if there's no open access point locally you wouldn't have to go through the list, looking at the encryption scheme that each of them uses, to find an available way to get to the internet?

XKCD looks at the logical extension to this system for accessing WiFi anywhere.