Hypothetical: To Sell Out or Not to Sell Out

So I was reading this article in the New York Times this morning, which talks primarily about brand names in teenage fiction, but it did bring up the question as to whether or not companies paid to have their products placed in the books. (Turns out no.) 

As a former advertising chick, my first thought was how smart (for the advertisers) and that competed with my second, writer-chick thought of no way would I do that in one of my books. 

It's certainly not the first time brands have been featured in books. I remember a litany of luxury brands in American Psycho which I found very annoying. I suppose that was the point. And I suppose if it fits the character, brand names can be useful in description. But what do you think about authors getting paid for it? Let's say Pepsi offered you a fat sum of cash if you would just write your MC as having an affinity for their soda? She cracked open a cool, refreshing Diet Pepsi before turning to him and saying...  

Would you do it? What the sum were REALLY fat? Obese, even.