Dave and Chris make good points, but two things jump out at me.

First Dave, the list is about the difference between what certain corporations say and what they do, not about which ones are harming the environment more.

Second and more importantly, while I agree that anything that can be done to get corporations to stop acting in ecologcially and environmentally harmful ways should be done.  However, it's harmful to allow corporations to claim they're doing something they're not, because if people believe them, people won't fight the harms they're doing.

So, we have to walk the fine line between encouragement and criticism.  It's an oversimplification to think that encouraging corporations in order to get them to do good without criticizing them when they lie about it will have a positive effect.  Very unlikely.

Good points all, as we struggle how best to dispense carrot for good behavior and stick for bad.  Most of the time I'm so disgusted with the mendacious, outright malevolent behavior of corporations that all I want is to reach for a stick and the bigger the better.  Unfortunately though, we are fighting this case in the court of public opinion as well as the courts of law and nobody likes a scold.  So every now and again if some corporation's pr team puts out a release that they've done something eco-friendly, we should balance out our usual stick with an appropriate amount of carrot.  I do however agree with jdhlax that if you are going to dispense some reward, it had better be earned.  Let's not sell our praise too cheaply.  People may not like a scold, but they certainly don't respect a chump either.

In interacting with corporations we're obviously dealing with entities who have the mindsets of five-year olds (very crafty, devious five-year olds, but children nevertheless).  The way they see things they are the center of the universe, their time-horizon stretches all the way to lunch or maybe naptime and they don't like being told "no".  With this in mind perhaps in teaching corporations how to think and act green, we should aim for the model of a Corporate Kindergarten ©.  Remember in kindergarten when everyone got a star to stick on their desks even whem all they did was show up at the right time with all articles of clothing on the appropriate limbs?  The kids who really excelled would get a gold star, those who were average would get silver and those who managed to quietly remain seated would get bronze.  Only if you were very very bad did you get no star and sent to the principal where you might get the stick (I went to elementary school in Texas).  

Yes, it's frustrating to have to jump up and down like it's Mardi Gras when all Walmart did was the bare minimum, and that because they were really trying to distract us from the bad things they did.  I wish we had better better corporations, just like teachers wish for better students.  As Dave pointed out though, it's much more practical to work with you've got.  Give Walmart their bronze or maybe silver star but do also remind them that the principal is right down the hall.