It has a lower TDP, so whatever the reason, it does run cooler at the same speed.
Here's a QX6800 with a 130 watt TDP and a Thermal Specification of 54.8C
http://processorfinder.intel.com/details.aspx?sSpec=SL9UK
Here's the E4300 with a 65 watt TDP and a Thermal Specification of 61.4C
http://processorfinder.intel.com/details.aspx?sSpec=SL9TB
Does this mean the 6800 Quad runs cooler than an E4300? I don't think so.
I'll wait to see some actual core temperature tests done using retail processors. A lower TDP doesn't seem to mean too much with Intel processors.