I have installed Ubuntu 12.04 on my EeePC 1015PX and I've noticed that the CPU temperature does not go below 60ºC (70 is usual). Looking at powertop it seems the 2 cores (Atom N570) are idle most of the time. I've installed jupiter (w/ jupiter-eee-support) but it did not help.
Edit: Meanwhile I've found out that
echo 2 > /sys/devices/platform/eeepc-wmi/cpufv is supposed to turn on Super Hybrid Engine. Though it seems to help a bit (temperature goes down 2-3ºC), the temperatures are still in the 60-70ºc range.