Anyone else noticed this, in SL in particular? The machine simply does not throttle back. You can confirm this with the power/sensors meter in iStat Menus; the CPU never fully idles or undervolts like it is supposed to. This doesn't happen all the time, it seems to be random. Nothing gets rid of it, until you reboot. Then things are back to normal for awhile, often days, or longer. I attached a screenshot as evidence. Activity Monitor to show the machine is idle, and netkas' CPU-X to show the clock speeds.