"Apple is in many ways a mentor company for us," Costolo told PBS interviewer Charlie Rose. He said the companies had "a great relationship." Facebook, by contrast, got this chilly description: "We're very different companies."
Facebook was pursuing symmetric networks, Costolo said, but Twitter saw the world as asymmetric. They were fundamentally opposed, and competed for ad dollars.
He also spoke of Twitter needing to have control over its own user experience. This was on the day that Twitter unified its experience across iPhone, iPad and the website (and produced an Android app that seemed to us more of an afterthought).
"We'll see how it evolves," was Costolo's judgment of Android. (He also said Twitter saw itself primarily as a mobile company -- taken together, an implicit endorsement of the iOS platform.)
This year has seen Twitter abruptly shut off API access to an increasing number of companies. It has also seen Twitter deeply integrate into Apple's Mountain Lion and iOS6 systems -- ahead of Facebook integration.
The interview gave us a lot of context on how Twitter sees itself, and what developers who depend on the company can expect. Costolo clearly stated he wanted a large ecosystem (just as Apple has), but hinted at one that was very strictly and centrally controlled (much like Apple's).