Markus M. Mobius of Harvardand Tanya S. Rosenblat of Wesleyan University conducted an experiment on the "beauty premium". Their study, "Why Beauty Matters," was published in the March 2006 American Economic Review. A prepublication version can be found here. The bottom line is that beautiful people are perceived as more competent, and also have more self-confidence. But, on the downside, they are expected to contribute more and are held to higher expectations.
Hal Varian has some thoughts on the study in his New York Times column "Beauty And The Fattened Wallet":
So perhaps beauty is a two-edged sword. If you are beautiful, people expect you to be better than ordinary-looking people, even in mundane tasks like solving mazes. But when good-looking people do not perform as expected, others feel let down. The rest of us can take solace in the fact that it is easier for us to meet expectations.So, being physically attractive is helpful in getting you in the door, but has downsides once you're in.
I try my best to lower people's expectations of my performance as much as possible, and I've usually been successful at getting people to "misunderestimate" me. Now I know part of the reason why.
Darn - I though it was just because I was shrewd...