Several years ago, the world was excited to hear about the development of single transistors that were capable of operating at 500GHz and above, then setting the speed record for the fastest syncing devices in the world. More lately, IBM and Georgia Tech have gone even further, and have developed a silicon-germanium processor that is able to compute at 350GHz room temperature and over 500GHz when frozen to -451 F. It gets even better for using germanium more frequently in modern CPUs:

To that end, IBM and Georgia Tech scientists turned down the temperature and cryogenically froze the chip at minus 451 F. It's about as cold as things get. An extremely cold temperature like that is found naturally only in outer space, but can be artificially achieved on Earth using ultracold materials such as liquid helium. Absolute zero comes at minus 459 F. SiGe chips, the scientists theorized, could eventually hit 1 terahertz, or 1 trillion cycles a second.
While you will not be seeing 500GHz desktop chips anytime soon, the advances in technology and the demonstration of the potential for the (more expensive) addition of germanium to chip making shows that there is plenty of room for growth in microprocessors.