Well, “people” is perhaps a generous term. Twitter is filled with automated bots Tweeting out, as well as feeds from publishers.
But other data suggests that Twitter’s audience keeps on growing. ComScore estimates that Twitter.com alone attracted 139 million unique visitors worldwide in May, 2011, a 54 percent annual increase. On a worldwide basis, Twitter is bigger than MySpace. In the U.S., however, traffic is up only 12.5 percent to Twitter.com, which attracted an estimated 27 million unique visitors in May, 2011.