This may shock and amaze you, but I'm taking a somewhat cynical view of this.
First of all, it's not like the environment needs to have awareness raised about it. It's the cause célèbre du jour, for crying out loud. It's like trying to raise awareness of Facebook.
Secondly, it's kind of gimmicky. Like that Live Earth concert that was more about music than the environment. I have a feeling this will be more about bloggers than the environment.
It's well-intentioned, and I wish them well, but I just don't see it doing anything concrete to help the environment.