One of the most interesting features of Intel's Core i5 and Core i7 processors is Turbo Boost, which can scale the clocks of individual cores beyond the base speed depending on load. Turbo Boost has gotten especially potent in Lynnfield and Clarksfield processors: the Core i7-820QM, for instance, can climb from a base 1.73GHz to 3.06GHz when one core is doing all the work.
This mechanism works pretty transparently, but it doesn't have to. Intel has released a gadget for Windows 7 and Windows Vista that lets users monitor the current fastest core clock speed of their Nehalem processor. Check it out:
The installer is an 18MB download, and it places the monitoring tool along with other gadgets in Windows' Gadget Gallery. As you'd expect, the Turbo Boost Technology Monitor will show up in the sidebar if you're running Vista and on the desktop with Windows 7.
Unfortunately, the tool seems to have no way of showing individual clock speeds for different cores—it just displays a single number corresponding to the fastest current core. The gadget definitely looks more sightly than something like CPU-Z, but it doesn't tell the whole story.