Actually, there are still strong oxen. Arguably, there are fewer people who need them, but they're out there. http://en.wikipedia.org/wiki/IBM_Roadrunner, http://en.wikipedia.org/wiki/Jaguar_(computer)#Cray_Inc.:_20..., http://en.wikipedia.org/wiki/Blue_Waters, and others on 1+ petaflop front are pretty exotic beasts, and run codes that require all 100k+ processors to work in tandem across their speedy interconnects.