There's really no problem with a muslim community center near ground zero, I don't see one and my philosophy's always been you need to get over loving 9/11. That being said, my philosophy's also that religion's loving stupid, so really my opinion is it's no less bad than building a church or other religious building there. In an optimum world there wouldn't be religion because people stopped being idiots (a future I think we're approaching if we don't blow ourselves up first), but I value freedom of thought even more than rationality as long as you're not hurting anyone with your thoughts (which I have trouble thinking will ever happen, it's your actions that hurt people).
Short version: there's no problem because islam's no more stupid than any other religion, but that isn't saying much, is it?