Intel’s upcoming Core i7 processors will feature a turbo mode, as announced on Day 1 of IDF. Although not quite like the retro turbo mode button found on computers of the late 1980’s, the turbo mode on Core i7 will still result in increased single threaded performance. The technology is based on the idea of dynamically increasing the frequency of the CPU when not all the cores are in use, archiving higher single threaded performance when that is all that is required
Source: Tom's hardware|Core i7 Will Self Overclock