In less than eight months, Facebook has doubled its user base by signing up 100 million people from around the world, officially hitting 200 million on Wednesday. Its population is now higher than Brazil’s and Japan’s. The ubiquitous online hangout, available only to college students when it opened in 2004, has been growing rapidly since opening up to anyone who wants to sign up. But how long can that continue? After a meteoric rise, News Corp.-owned MySpace has petered off and now has roughly 130 million active users, according to comScore.
