Going Green...Start with Plastic Bags...Tax or No Tax?

Rather than wait for policy changes, I feel that we can Go Green (or at least Greener) with simple steps.
One of them is shunning plastic bags.
Some stores do not make it easy and others like Whole Foods for example encourage you by crediting 10c for each bag brought back with you.  
In Taxes with a greenish hue, Elisabeth Rosenthal (Business of Green) wonders if voluntary measures are enough.