It turns out that the Intel RC6 power-savings feature
can be pushed even further.
A patch was published that allows Intel RC6 to be pushed into its deepest state under Linux for conserving system power consumption while also improving performance in some workloads (as shown in the aforementioned Phoronix article), but what's to be on by default in the Linux 3.2 kernel (and can be manually toggled for older kernels) isn't the deepest.
The deepest state should drop the power consumption by another half Watt or so, depending upon the hardware.
However, it seems that there may be some caveats with this deepest Intel RC6 power savings state as is being discussed right now on the Intel Linux graphics mailing list