It’s really difficult to change a company’s culture, but I did this by making sure I stayed late,” he says. “I’d go home, have dinner with my kids and then come back into the office. People knew that if they were in the office at 10 p.m., I’d be here, too, and that’s when I would go around and talk to people and answer questions.

Dick Costolo of Twitter, an Improv Master Writing Its Script - NYTimes.com

Not much meat on the Bilton piece about Twitter/Costolo, but this passage strikes me as odd; not sure how a culture optimizes staying late at the office is achieving what its goals should presumably be: deliver great experiences, innovate, and not pissing on your users.