I was bit disappointed to find this article had absolutely nothing to do with power management - it should have been called "Power Consumption: ATI Catalyst vs. Open Source ATI Driver" IMHO.
Power management, in this case, is having your video card automatically use lower core/memory clock speeds (and whatever else can be done to save power without losing functionality) to save power when one is not using 3D and has no need for full power and full clock speeds.
I wanted to know how far along the power management support in the open drivers was. Does the card automatically clock down for 2D? And clock back up for 3D? Does it do this reliably, ie: doesn't stutter in 3D jumping back and forth between clock speeds? Does it stay at 2D clock speeds when using 2D or does it jump higher for some tasks(if so, is that noticeable?)? Does it share the same ridiculous limitation as fglrx (plug in a second display and PowerPlay ceases to clock down AT ALL)? How far does it clock down? Is it too far to keep a 2D desktop snappy? These are some of the things an article purporting to compare power management features between 2 drivers should be testing (and obviously what power savings can be had in the process). Not power consumption at idle and under load when no power management features are even enabled..