Facebook now has >300m active users

"General Growth
More than 300 million active users
50% of our active users log on to Facebook in any given day
The fastest growing demographic is those 35 years old and older
User Engagement
Average user has 120 friends on the site
More than 6 billion minutes are spent on Facebook each day (worldwide)
More than 40 million users update their statuses at least once each day
More than 10 million users become fans of Pages each day
Applications
More than 2 billion photos uploaded to the site each month
More than 14 million videos uploaded each month
More than 2 billion pieces of content (web links, news stories, blog posts, notes, photos, etc.) shared each week
More than 3 million events created each month
More than 45 million active user groups exist on the site
International Growth
More than 65 translations available on the site
About 70% of Facebook users are outside the United States
Platform
More than one million developers and entrepreneurs from more than 180 countries
Every month, more than 70% of Facebook users engage with Platform applications
More than 350,000 active applications currently on Facebook Platform
More than 250 applications have more than one million monthly active users
More than 15,000 websites, devices and applications have implemented Facebook Connect since its general availability in December 2008
Mobile
There are more than 65 million active users currently accessing Facebook through their mobile devices.
People that use Facebook on their mobile devices are almost 50% more active on Facebook than non-mobile users.
There are more than 180 mobile operators in 60 countries working to deploy and promote Facebook mobile products"
Source: Official Facebook Statistics, retrieved 16th September 2009
Earlier figures here (250m active users, in July 2009)