I more or less act the same way offline as I do on. However, my nastiness is more humorous than serious.
I totally agree with that article, though. You know what's funny? People will talk to you like shit over the phone. They'll talk to you like shit online. In person most carry themselves with at least a small modicum of decency. However, if you work at a store, no matter if you're a brilliant college student trying to make a buck or just some deadbeat, people will treat you like a piece of shit face-to-face.
That's the one that always makes me scratch my head. I can see the anonymity being a factor in the other cases, but what's the excuse there? I'm guessing because the person is on a payroll and can't react without losing his or her job. Makes the cowardly dregs of society feel big and important when they've got someone to talk down to.