I don’t have a white paper (yet). It really depends on the business context as to how many successful customer interactions happen.

It is a matter of finding the people who need help. Tools like Radian6 are good at this, as they very complex search mechanisms. However, companies with unique names (DIIGO, JungleDisk) are easier to find mentions of using simple search tools. When you find people in need you are more likely to have a interaction with a customer.

So long as you invite feedback online and do something about any comments you see, they will keep coming.

In my experience, at the start there are only a few really frustrated people who tweet, but with time, when people know you are there they may choose to interact through Twitter.