It hasn't been fair to compare single-CPU performance in a long time, machines on the top500 either use commodity x86-64 chips, or (BlueGene) much slower chips with good memory and power efficiency (NEC is a notable exception). But it's worth noting that supercomputer performance consistently outpaces Moore's Law (http://59A2.org/na-slides/Keyes-PetaflopsSeriously-2008.pdf).
