At the annual South by Southwest gathering of techies in Austin, Tex., in March, conference organizers had chosen a hangar-size room to accommodate their star speaker: Evan Williams, the co-founder of Twitter, the messaging and social networking site that had become a digital phenomenon.
In a private moment before the doors opened, Mr. Williams, who is famously deliberate and cautious, snapped a photograph of the endless rows of chairs facing the stage and posted it on Twitter.
"Gulp," he wrote.
Later, as Mr. Williams talked with the interviewer about building a 21st-century business, keeping to Twitter's foundational principle (the Google-like "be a force for good") and fostering corporate experimentation, members of his audience started groaning -- and leaving, one by
