Twitter said Monday the company appointed Dick Costolo chief executive officer. Co-founder Evan Williams stepped down to focus on the company's product strategy. About 300 employees support 160
million registered users who tweet about 90 million tweets daily.
In a prepared statement, Costolo talked up the position at Twitter, the team members, and projects in the pipeline. "We're
ready to accomplish more in the next two years than we've accomplished in the last four," he said.