Yelp recently sponsored a bake-off between a Naive Bayes classifier and the online crowd-sourcing site Mechanical Turk. The task was classifying web sites according to their business category (i.e., is it a restaurant or a doctors office?). The classifier beat the turkers handily:
In almost every case, the algorithm, which was trained on a pool of 12 million user-submitted Yelp reviews, correctly identified the category of a business a third more often than the humans. In the automotive category, the computer was twice as likely as the assembled masses to correctly identify a business.
There are a variety of qualifications (why did 99% of Turkers who applied for the task fail the basic test? ESL issues perhaps?). But it's an interesting result.