The polls already out suggest that this has NOT harmed Bush all that much. It will resonate with the "Undecideds" in the big show of 2008, the theme of which for the Democrats will be "Incompetence."
That is of course, unless Rove's "Mexicans are the Republicans of the Future," suddenly show up at the polls.
Remember Grover Norquist in '98/'99 saying that Muslims were the Republicans of the future?