A few days ago a post on BicycleSpokesmen.com brought the issue back to mind. This article pointed out the oddity that new park rules had been proposed to allow concealed-carry weapons in national parks (in states where concealed-carry is already legal) and that one seemed more likely to go through than did the rule change to allow bikes in parks.
The way I see it both groups mentioned above (cyclists, gun owners) are the victims of the public image of their membership but we don't have the benefit of being included in the Bill of Rights. As long as the public image of cyclists comes mainly from news footage of fights between cops and Critical Mass riders we're going to have an uphill battle.
Unfortunately, the hill we have to climb isn't one in a national park.