The EPA is hoping that the new Energy Star rating for data centers will become a selling point for data centers. The new rating is based largely (but not completely) on the PUE (or Power Usage Effectiveness). William Kosik wrote an article in the September 2007 issue of Engineered Systems Magazine that explains PUE quite well and in detail.
Google talks about their efforts for power-efficient computing in their data centers in some depth; it’s very interesting.
IBM also announced just recently that they are building a new data center in Research Triangle Park where they will test effect of various temperature levels in the data center – and will cool it with outside air as well.
This is definitely an exciting time for data center power research; seems that there is something new every day.