Facebook has more than 800m active users (full stats)

"People on Facebook
More than 800 million active users
More than 50% of our active users log on to Facebook in any given day
Average user has 130 friends
Activity on Facebook
There are over 900 million objects that people interact with (pages, groups, events and community pages)
Average user is connected to 80 community pages, groups and events
More than 2 billion posts are liked and commented on per day
On average, more than 250 million photos are uploaded per day
Global Reach
More than 70 languages available on the site
More than 75% of users are outside of the United States
Over 300,000 users helped translate the site through the translations application
Platform
On average, people on Facebook install apps more than 20 million times every day
Every month, more than 500 million people use an app on Facebook or experience Facebook Platform on other websites
More than 7 million apps and websites are integrated with Facebook
Mobile
There are more than 350 million active users currently accessing Facebook through their mobile devices
There are more than 475 mobile operators globally working to deploy and promote Facebook mobile products"
Source:  Facebook Statistics, retrieved 27th September 2011