From a US Fish and Wildlife Service press release:
_The U.S. Fish and Wildlife Service today announced that effective February 22, 2010, the rules governing possession of firearms on National Wildlife Refuges will change as a result of legislation enacted by Congress. After this date, the law allows an individual to lawfully possess a firearm within the boundaries of a National Wildlife Refuge in accordance with federal and state firearms laws. . . .
_The new law applies to all 551 units of the National Wildlife Refuge System, as well as the National Monuments and the 392 units of the National Park System.
While the law will change the application of rules regarding possession of firearms, it has no impact on the authorized uses of firearms on National Wildlife Refuges. The law does not allow visitors to fire or discharge the firearms in any way, brandish the weapon in the view of others, or any other use of the firearm. Enforcement of regulations concerning firearms use remains under the purview of the Department of the Interior.
In short, the law does not expand hunting opportunities or any other authorized use of a firearm beyond what is already allowed within the Refuge system. But–and this is the bottom line–it does let you possess a firearm in a bunch of places where you previously couldn’t.