Ten minutes after his maiden tweet he had 10,000 followers. His next 10,000 came in the following half-hour.
(Read more: Twitterverse reacts to Apple chief's first tweet)
Cook was slowly adding people to follow as well, with Anderson Cooper, Kings of Leon, Jimmy Fallon and Duke Basketball among his first 10. One other is Steve Jobs' widow, Laurene Jobs, whose Twitter presence is enigmatic—she's never tweeted and follows no one. She does, however, have more than 2,000 followers.