Twitter started selling ads -- sort of -- in a modest attempt to get the Twitterati used to the idea that the start-up, valued at $1 billion based on private placements, is entitled to make serious money. So far, the sky hasn't fallen.
Twitter doesn't need to make a lot, operationally. The company has fewer than 200 employees and manages a sea of servers. Tech support, marketing and maybe one HR person.
In an interview with BBC radio, I talked about what Twitter is doing, what they aren't doing, and what they might do. I might have used the "dip their beak" metaphor instead, if I had thought of it. But on second thought, I'm glad I didn't. Hate those forced metaphors.