"In many ways, Twitter is a re-incarnation of the old Unix philosophy of simple, cooperating tools. The essence of Twitter is its constraints, the things it doesn’t do, and the way that its core services aren’t bound to a particular interface."

Tim O’Reilly.

And:

“There’s a real lesson to Facebook here about giving other services (like Twitter) access to their social graph. They have the best one going, but because they try to keep users coming back to their interface, and even the applications built on their service have to live in Facebook, they end up as a ghetto rather than a true internet service. It’s the data, not the interface! Let other people use your data, build on it, and it will still belong to you. Hold it too tight, and they will compete with it.”