The USDA is looking for comments on a proposed definition of "grass fed," for an addition to its Process Verified Program (via Growers and Grocers). Believe it or not, right now the agency is considering requiring that 99% of an animal's energy come from "grass or forage" (yay!), up from 80% in the original proposal — which would have allowed cows finished in feedlots on grain to still qualify for the label (boo!)
The organic meat, fish and poultry market experienced the highest growth last year, 55%, of any food category. I know "organic" and "grass fed" often don't refer to the same meat, but I'm sure Big Beef has an army of lobbyists working on watering down the USDA's definition.
So find a stamp: The Sustainable Agriculture Coalition has a downloadable PDF with more information and a letter you can mail to the USDA, reiterating how important it is for the 99% requirement stay in so that the "grass fed" label will mean something.