Well there you have it, there are now a billion people using Facebook actively every month. Mr Zuckerberg pushed out a status stating the new stat just a few minutes ago (as of writing this). Only a month or two or ago was there 950 million active users. So it looks Facebook is still growing and will probably do so with their being around 7 billion people in the world and with more and more of them gaining internet access.
I'm sure a bunch of them are fake accounts too, ex-girlfriends be crazy right?