This should be an interesting thread, I think.
I've even heard my liberal friends saying we shouldn't allow it because the families of the 9/11 victims don't want it.
not knowing whatothers have said, here are my thoughts:
the muslims are not dumb and they would know that seeking permission to build near ground zero would cause problems. they may have the right to build there but they should have enough sense to decide not to.
but arabs are known for building over important sites of non-muslims that way they can claim it is muslim hioly ground and bar others form it. we see this througout the middle east, especially in israel and where former byzantine churches had been built.
now i am thinking that the right to free religion does not include constructing buildings and such can be barred by the government if they so choose without worry. regardless of the precedent of previously constructive religious structures.