Most twitter users don't tweet, they just follow. Getting the big users on board and figuring out they everyday people don't need to tweet was one of the big epiphanies.

If you look at the google trends, they were basically stagnant until 2009 when they made that realization and focused on activating users by getting them to follow a certain number of consistent tweeters.

With consumer stuff, nothing is ever cemented, but I can assure you that RG is doing quite well wrt to growing that community.