The team of scientists behind this endeavor have accomplished this massive speed increase (500GHz) by cooling down to 9 degrees above absolute zero using liquid helium. For those of you who aren't familiar with absolute zero, it is the lowest temperate possible, the temperature at which even molecular vibrations cease and everything is frozen. This temperature is comparable to that found in outer space.
The team includes researchers from Georgia Institute of Technology, Korea University, and IBM whose results will be published in IEEE Electron Device Letters, a technical journal. Their efforts have produced a Silicon based chip that operates at 250-times the speed of chips common today. Previously, it was believed that such speeds weren't possible purely due to the heat produced from operating a conventional chip. Even at room temperature, the new chip can run at speeds up to 350GHz.
These results are significant because it demonstrates that the chip industry has not yet reached its upper limits, something many have been speculating over and fearing for years. But it is important to know that such technology is far from finding its way into commercial products any time soon and that sheer processor speed is not the only factor in determining a better CPU.