Facebook crosses one billion active users mark
According to Facebook, this figure breaks down as 4.8% duplicate accounts, 2.4% what the social network terms "user-misclassified accounts" and a further 1.5% spam or "undesirable accounts."
These figures lower Facebook's number of MAUs to around 872 million; in comparison Twitter's number of users was estimated to be around 517 million (including spam accounts) in a July 30 report by Semiocast.
Read Facebook's full 10-Q report at: http://goo.gl/K1yoK