Meh, easily avoided. Just do a captive portal redirect to "google.johnsmith.example.com" with a properly signed certificate, add google logo and login fields,

Meh, easily avoided. Just do a captive portal redirect to "google.johnsmith.example.com" with a properly signed certificate, add google logo and login fields, and after a user enters his credentials, just redirect them to actual google.com. Most people don't look at domains in the url. You can actually probably register a domain like "freegooglewifi.com" or something.