No I dont know how quick a petaflop is...
IBM just announced its 20-freaking-petaflop Sequoia supercomputer due for delivery by 2012. While supercomputer speeds have steadily increased year-over-year, a near 20x jump in calculations per second since the last world ranking is unheard of, even if the system has yet to come on-line. Slated to spend its life simulating nuclear explosions, Sequoia will use 45-nm (PowerPC, presumably) processors with 16 cores per chip for as many as 4,096 processors per rack. That's a total of 1.6 million cores assisted by 1.6 petabytes of memory
1.6 million cores....your average PC has a dual core or quad core processor, so can run 2 or 4 things in parallel. So imagine running 1.6 million things in parallel!
I cant even imagine how you program that bad boy!