36/sec but then they're doing 800 http requests per second, not sure what could cause such a big difference (lots of ajax stuff?) but I think 800/sec is an interesting thing to see them deal with, that's something in the region of 1bn a month, which fits your requirement for interesting-ness :p
Sorry, the threshold of interestingness for serving static assets is even higher. ;)
A single nginx on a moderate host will barely warm up before ~10k reqs/sec. The network tends to be the bottleneck here. Anyways, ~800/s should be doable from a $10 VPS.
