IS THE GROUND ZERO MOSQUE AT GROUND ZERO?

Yes.   Rich Lowry:

If you wanted to locate a mosque at Ground Zero, it’s hard to see how you could get much closer. The title of the Malyasian edition of Imam Feisal Abdul Rauf’s book, "A Call to Prayer from the World Trade Rubble," is not far from the mark, and Ground Zero mosque seems an appropriate, loose way to refer to his project.      [my emphasis]