Japan will begin developing a new supercomputer that will be able to perform more than a quadrillion calculations per second by 2010. This supercomputer will be almost 30 times faster than Japan's fastest supercomputer; the Earth Simulator from NEC which handles 36 trillion calculations per second.
World's fastest supercomputer is the IBM Blue Gene/L which boasts 70.72 trillion calculations per second.
The new supercomputer will be used for medical simulations to see how drugs are dissolved and how they effect organs. It can also help to improve weather forecasts. More details at Reuters