Evan Williams steps down; Jack Daniels to lead product development.

Washington Post: Evan Williams: Twitter CEO no more

In keeping with Twitter’s ethos, Evan Williams, the chief executive of the micro-blogging social media site, took less than 140 characters to announce the company’s latest strategic change. He took 133 characters, to be exact: “I have decided to ask our COO, Dick Costolo, to become Twitter’s CEO. Starting today, I’ll be completely focused on product strategy.”