Furthermore, since Facebook stores four sizes for each stored photo, this actually translates to 40 billion files. However, what I find fascinating about this is that Facebook is no Photobucket; it's not just some repository (at least from what I've seen) where people dump all kinds of images just because they can. Vast majority of photos I see on Facebook are actually real life photographs taken by users; I'm not sure if this means much in the grand scheme of life, universe and everything, but it seems like quite an accomplishment.
If you're the number crunching type, here are some other facts and figures from Facebook's photo vault:
* 2-3 Terabytes of photos are being uploaded to Facebook every day
* They have just over one petabyte of photo storage
* They serve over 15 billion photo images per day
* Photo traffic peaks at over 300,000 images served per second