FaceBook is encountering the same problem it had a few months back. Hundreds of messages in the support area from users reporting that photos they've uploaded are "missing".
The albums are still there, but instead of seeing photos a small blue square (a checkbox for a form) appears instead. Many users report entire albums of photos missing and other are seeing only some photos and not others.
The last time this happened FB said it was a hardware problem and that no data or image files were actually lost, just temporarily unavailable until they fixed the problem.
FWIW -- I was looking into it because about 1/2 of my photos are "missing".
I noticed this started happening on friends pages about 2 weeks ago. Eventually the pictures would load or if I stopped the page load and clicked the empty image placeholder the link would still work and display the larger size of the image. An appropriate subtitle you have offered this discussion ... "The price of success ..."
An article in March (on InsideFacebook blog) estimated the total number of FB user photos to be somewhere around 14 Billion... at that time they estimated 10-15% missing, (meaning over 1 billion "missing" images)...
I wrote "The price of success" because it's obvious FB can't keep up with the sheer volume of photos people are uploading -- and the numbers are growing.
Facebook has become the largest photo sharing site on the web, (outpacing Flikr, Photobucket, Shutterfly, SnapFish and other sites who's core function is photo sharing.