I was working with a couple of guys on the TechPowerUp site today and their 45nm Quads appear to have at least 15C of slope error. For users with sensors that are reading too high, the official release of TjMax=100C hasn't done them any good. It's just made things worse. With this much error in some of these sensors at idle, it's no surprise that Intel didn't want to tell us too many details at the IDF.

Burebista on TPU posted some results from X-Bit Labs showing that an E8400 consumes approximately 3 watts at idle. With a big air cooler or water, my assumption that idle temps are only about 5C over the surrounding air temperature still seems reasonable. The new E0 series allows the processor to enter C4 power saving mode for even more power savings and low idle temperatures.