If it happens... there has been substantial opposition. Somewhat surprisingly to me, the bulk of the opposition has come from park rangers. I guess I shouldn't be surprised, police organizations have traditionally opposed concealed carry as well (though the lack of negative result seems to have changed some of their minds -- and plenty of individual cops have always been supportive).
The latest is that they're asking for the decision to be delayed until after the Supreme Court rules on DC vs Heller.
I'm keeping my fingers crossed, and providing my opinion at every opportunity, but it's far from a done deal.