From today's Wall Street Journal article "Tensions Rise Between Facebook, Developers:"
Last month in Paris, developer Antoine Morcos received an unexpected email: Facebook said it was cutting ties with his photo-sharing application, Vintage Camera. Mr. Morcos, 31 years old, instantly lost nearly half a million registered users who only accessed Vintage Camera through the social-networking site. Facebook, without being specific, said too many users had complained about Vintage Camera, said Mr. Morcos. He appealed, arguing his app fielded less than three complaints for every 1,000 photos shared, but Facebook didn't budge. "I was really shocked," Mr. Morcos said. "Users were sharing as much as 6,000 photos per day on Facebook; now access is blocked."
Vintage Camera, which competes with Facebook's Instagram app, is one of a growing number of third-party apps that have been blocked by the social network recently. Facebook has long had a complex relationship with developers as it balances a complicated set of interests. The company says it is stepping up efforts to police the network by curbing spam and restricting apps that aren't adding sufficient value to the network. Developers say the crackdown is an attempt to stifle applications that compete with Facebook-owned services or part of an effort to get developers to pay for ads on Facebook...
On Friday, Facebook blocked MessageMe Inc., a messaging service that had just launched days earlier, from accessing users' friends list. Arjun Sethi, a MessageMe co-founder, said Facebook cited a section of its policy that addressed restricting apps that copied a core Facebook product or service. According to people familiar with the matter, the fledgling service had recently rebuffed takeover interest from the social networking company.
To see what makes Facebook tick, you might look into how it all started by reading Ben Mezrich's novel The Accidental Billionaires (which was the basis for the film The Social Network):
Best friends Eduardo Saverin and Mark Zuckerberg had spent many lonely nights looking for a way to stand out among Harvard University’s elite, comptetitive, and accomplished student body. Then, in 2003, Zuckerberg hacked into Harvard’s computers, crashed the campus network, almost got himself expelled, and was inspired to create Facebook, the social networking site that has since revolutionized communication around the world. With Saverin’s funding their tiny start-up went from dorm room to Silicon Valley. But conflicting ideas about Facebook’s future transformed the friends into enemies. Soon, the undergraduate exuberance that marked their collaboration turned into out-and-out warfare as it fell prey to the adult world of venture capitalists, big money, lawyers.Keep in mind that since Mezrich's sources were Zuckerberg's enemies and not Zuckerberg himself, you should take the account with a grain of salt.