These guys clearly do not care much about the costs right now... the more they grow the larger the drag is going to be, though. I have heard from a solid source that they're storing these images in BigTable. So, they're probably paying 0.18/GB a month (or maybe less with a deal) and then also paying for the reads and writes as units, and then also for the bandwidth (which is amplified by the # of recipients). I'm not sure if you could find a more expensive way to store images if you tried. Being in GAE means they wouldn't have peering arrangements, so they are paying top-dollar for GAE BW, where a FB or Google is paying for a fiber run and some rack space. SC are very green when it comes to the business of shuffling bits, and if they want to really play with the big boys they will have plenty of catchup to do. Google is making lots of money off them, which makes me wonder if that was part of the FB play.