Some day :( http://www.technologyreview.com/computing/24482/page1/

We've definitely reached the limits of traditional silicon transistors, long ago, in fact. At temperatures at or above ambient room temperature, transistors seem to max out at somewhere between 4-5GHz, depending upon CMOS process characteristics (SOI, HKMG, etc.). At sub-ambient temperature, clock speeds as high as 8GHz can be realized. I doubt we'll be seeing chips with significantly higher clockspeeds any time soon. More IPC and more concurrent threads is the paradigm for the foreseeable future.