Intel used such a technology, called Speedstep, since 2000, but is now being asked to pay damages, license fees, and attorney's fees in a patent infringement suit.
The suit was filed by Frisco, Texas-based Power Management Systems, which claims rights to a patent that describes a "power management apparatus collocated on the same integrated circuit as the functional unit that it manages."
The patent was filed in January 1994 by Dublin, California-based Electronics Products Company and was granted in April of 1996. There was no information how that patent found its way to Power Management Systems and why the patent infringements complaints are now filed more than 10 years after Intel introduced this technology in its products. It is interesting to note that the plaintiff does not target the entire processor line of Intel, but just the Atom 600-series of CPUs.
However, the case could set a precedence and may only be limited because of simplicity and cost reasons at this time. If a patent violation is confirmed, Intel (and others) may be on the hook for substantial damages and license payments. Regardless, it's unlikely that Freescale, Marvell and Intel will simply roll over and pay.
If the OS doesn't support the powermanagement features, they are not activated. So in a way it requires software. So its not like the cpu throttles itself.