CHICAGO: Oprah Winfrey joined Twitter, promising some competition for fellow Twitterer Ashton Kutcher, who has attracted his one-millionth follower.

Winfrey posted her first Tweet during The Oprah Winfrey Show on April 17, which featured Kutcher and Twitter CEO Evan Williams. As of that afternoon, @Oprah had more than 138,000 followers.

On April 14, Kutcher challenged CNN to see who could get to 1 million Twitter followers. CNN reported that, as of Wednesday afternoon, Kutcher had 896,947 followers which ...