The Phoronix tests were worst case scenarios and not really complete. They tested Ubuntu 11.04 Beta against older versions of Ubuntu on a limited number of IBM Thinkpads of varying ages and all tests were at or near maximum capacity for the systems.
They did not test other distros, other manufacturers' systems, or operation at light loads. Results varied somewhat from one Thinkpad to another with older systems showing the largest increase in power usage.
I do not think this will be a major problem for the average user who seldom or never pushes his system beyond 25% or so of maximum capacity. And even for the power hogs, the main problem will most likely be shortened battery operating time rather than overheating.
Registered Linux User 483387