When...
the fuck are people going to stop using public email services to carry out highly secretive government business?
And I'm going to somewhat resignedly answer myself here;
When they don't want to hide the illegal/embarrassing shit they're doing from the people who they represent.
I know, he's a hacker, and like boo for illegality. But if you have nothing to hide on public office, why do this, unless you're ignoring basic security protocols because you're an idiot.
That said: if it's good enough for Bush, Palin, Clinton (ms), Gove, and who knows who else...yet...