Here are two recent reports looking at the hardships in Greening-up a Data Center.
Curiously enough, being green also helps get in the black as decreased energy consumption means decreased costs.
As Mark Bregman, executive vice president and chief technology officer at Symantec, says in the articles, "The report findings indicate that cost savings and constant business pressure to maintain performance and meet increasingly aggressive service level agreements are the main reasons for implementing many green strategies. For them it is beyond environmental concerns; it is about meeting business goals and reducing costs."
This should come as no revelation. Reducing waste, recycling where possible, minimizing power usage are all cost effective measures while also being environmentaly friendly.