Forrester was citing PC power management as one of the main power savers we can enable in 2009. They also neatly debunked 5 myth people frequently come up with:
Myth No. 1: The power used turning my PC on negates any benefits of turning it off.
"Not true, leaving it on over night costs 1.42 kWhs, which you never use turning it back on."
Myth No. 2: My screen saver is saving me energy
"Aaaah c'mon, that's just silly".
Myth No. 3: Turning my PC on and off will reduce its performance and useful life.
"Modern PCs can handle up to 40.000 on/off cycles."
Myth No. 4: I can't run updates and patches for PCs in lower-power states.
"Wake-on-LAN" technology can actually enable this."
Myth No. 5: My PC users will not tolerate any downtime for power management.
"I don't even follow what users would complain about here..."
All in all, solid support to stop wasting large quantities of energy for nothing.