I imagine they improved the cooling of the new 360, as well.
My 360 is a space heater, man. In the Texas summer, 20-30 minutes with my 360 on will bring my room up to a sweltering temperature. I bring up the hot summer here because my room has two windows which have the sun shining right onto them for the majority of the day, so my room is mildly comfortable even with the A/C cranked, but when the 360 gets turned on, it pushes the ridiculousness over the edge (read: sweating like crazy).
On the flipside, during late fall and winter, having my 360 on instantly brings my room to a very comfortable temperature.