Senior pictures were a huge and expensive deal where I grew up (Battle Creek, MI). You essentially had a multi-hour session with a portrait photographer and perhaps various props from your life (in my case, there were many shots with my French horn). I actually ended up having my session redone after my mom saw the proofs and suggested, very politely, that perhaps the large Amish beard I was sporting at the time wasn't the best look for posterity. I wonder what happened to those proofs? (The second session wasn't a whole lot better, sadly, as you can see.)
Anyway, senior pictures ended up in the yearbooks (much larger than the pictures of the underclassmen), but we also handed them out with personalized inscriptions on the back (or not, if a snub was in order). There was even a rather ugly socioeconomic class aspect to it all, wherein there were cool photogs and not-so-cool photogs, correlating roughly with their fees. And it was definitely not socially acceptable to get the pictures at Glamour Shots or a mall portrait studio.
All of this was largely pre-Internet and pre-digital photography, and I have no idea how this works now in the age of Facebook and pervasive digital cameras, but I'd be really curious to see it in a novel.
Bonus: Check out this NPR piece on China, featuring fascinating details about the phenomenon of "Barbie photos" for middle-class Chinese teens. Really. Interesting.
