"Today, thanks the Facebook IPO filing, we have an update to the official numbers: there are now 425 mobile monthly active users as of December 2011"
—
Facebook’s Mobile Monthly Active Users Grew 21% Over Past Four Months | TechCrunch
This situation should be common to most major online properties— staggering growth in mobile actives (vs. desktop) but monetization is lower and engagement metrics are lower (not sure if this last point applies to FB).
Definitely not a simple solution here and a risk factor that affects a broader category of companies than just Facebook.
