OK, I realize that the number of businesses using Macintosh computers is completely dwarved by Windows installations, but that doesn't mean they should be left out of the effort to manage power better at the corporate desktop.
That's why Faronics has updated the Macintosh edition of its Power Save software (now in version 3.0) in order to provide better energy consumption reporting through the Faronics Core Console enterprise management tool. The new version of Power Save for Macs can now automatically figure out what sort of Mac you're using, figure out the appropriate electricity usage information and produce a report about same. Better still, an update to the Windows version of Power Save (now in version 3.3) means that you can manage BOTH Windows and Mac systems from the same Core Console, so that you can get a better picture on mixed deployments. Here's more information on the basic feature set of Power Save.
If you're already using Power Save and you have a maintenance contract, you can download the updates at this link.