While we were on stage, Jack asked me to come back to work at Twitter. People cheered. But I wasn’t really sure if he meant it. After Tea Time, we spoke privately and Jack told me that he really did — he wanted me to come back and work at Twitter. The company I co-founded, the service I co-invented. I was stunned, but I knew the answer.

Other companies have brought back their founders—it has worked very well for some (Apple), and not so well for others (Yahoo).