Whist we're at it I'd love to see the stats for twitter. How many of their users are actually active? Or those active users how many are real people an not bots?
I have not used my Twitter account for over two years, yet it gathers about 3-4 new followers a week so there's a significant amount of pointless activity created by automated processes that just follow people based on keywords - or maybe there's a lot of people who like my extended period of thoughful silence.
The spam followers I pick up seem to target lists of “followers of X”, where X is marginally topical to their spam.