Edit (July 12, 2006): I have learned something, thanks to this article posted by Christof, and a talk with Adam Malinowski.
The way I now understand it, GHz is just the frequency chips run at and, contrary to what Intel has led us/me to believe, is not necessarily a rating of speed. Using MHz and now GHz as a rating was, as I understand it, done by Intel for marketing reasons. In fact, AMD processors that run at a lower GHz rating are often faster. To compete with Intel, AMD began assigning â€œPower Ratingsâ€ to their chips. For accurate speed ratings, we should look instead at benchmarks.
A prototype that is more than 100 times faster than regular desktop PC chips has taken the world record for the world’s fastest silicon-based microchip, clocking speeds of up to an astounding 500GHz. Needless to say, the chip was kept cool with liquid helium. Further advancement in this field could eventually lead to faster wireless networks and more affordable cellphones to get the entire world connected as new applications crop up and the costs for existing products plummet. By comparison, the fastest Pentium processor available from Intel today runs at speeds of up to 3.8GHz.