It's a noble effort, with 539 signatories to date, but it has no teeth: no firm deadline for offsetting greenhouse gas emissions and no penalty for not doing so.

FORBES: America's Greenest Colleges

Many schools have pledged to go "carbon neutral" by offsetting their greenhouse gas emissions by investing in CO2 reduction efforts elsewhere.

FORBES: Magazine Article

Google says it has been carbon neutral since 2007, offsetting its greenhouse gas emissions by signing contracts to purchase renewable energy from wind farms and the like and by buying carbon credits that help finance other green power projects.

FORBES: Google Reveals Its Carbon Footprint