Hey you, don't be so rude. Was that effective? Do you prefer: excuse me, sir, but would you please mind how you speak to me? I thought so! As this brilliant article points out, your skills may get you in the door, your manners may well seal the deal.
Manners are just as important in the workplace as they are anywhere else in life: at home, at a restaurant, at church, etc. You wouldn't talk down to your spouse (at least I hope not), so neither should you to your colleagues.
What the article points out is that it's the little things that might endear you to a company or your colleagues. For example, saying "please" or "thank you" instead of demanding alpha-male style will likely make your colleagues more than happy to work with you or assist you in the future.
Having manners doesn't mean that you can tell the difference between a fish and a steak knife (though you should), but it means recognizing the right touches to make your fellow employees feel human and respected.