A pretty good post at Read/WriteWeb on You can make money on the long tail but not in the long tail:

"..It is often forgotten that money is to be made by leveraging the collective long tail, however, making money while being part of the long tail is very difficult. Specifically, in the blogosphere, the vast majority of blogs have very few readers. It is not realistic to expect these blogs to make money. As the enthusiasm and the incentive in the long tail begin to wear off, what would be the impact on the businesses that depend on them? Likely, the impact is going to be large."