That’s a tricky question. As you know, we just defined greenwashing at Whatis.com, an addition which reflects the amount of effort companies are now putting in to appearing green, if not actually becoming so in their manufacturing or e-cycling policies.
There are some standardizing bodies that certify products or services as green (GreenSeal.org, for example), or that regulate corporate actions, notably the EPA.
Deciding whether many companies or products are in fact as green as they is often ultimately decided in the court of public opinion, influenced by great investigative journalism or advocacy by groups like Public Citizen, PIRG, Greenpeace and the Sierra Club.
The Energy Star ratings for PCs and data centers are well respected as well, along with LEED certification from the U.S. Green Building Council.
Another important standard is the Environmental Product Environmental Assessment Tool, or EPEAT, an environmental attribute ratings agency for notebook and desktop PCs and monitors.
White House Executive Order 13423 requires federal agencies to purchase at least 95% EPEAT-registered products in all relevant electronic product categories, which may drive purchasing decisions in the private sector as well.