Mobile MAUs were 1.01 billion as of March 31, 2014,
an increase of 34% year-over-year.
That's crazy. 1/7th of the world's population logs in to Facebook from a mobile device at least once a month.(edit: as it turns out, these numbers are from the 1st quarter. Q2's show 1.07 billion mobile MAU: http://investor.fb.com/releasedetail.cfm?ReleaseID=861599)