IBM's Roadrunner is currently classed as the worlds fastest Supercomputer with 1.105 petaflops however IBM think this is a little feeble and have just announced the Sequoia supercomputer due for delivery in 2012. This badboy will offer nearly 20 times the calculations per second than the previous Supercomputers which is a ridiculous 20 petaflops. 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.
Unfortunately it wont run Crysis on ultra high settings.