From this:

Illegal immigration appears to have fallen last year, marking the first drop in years and coinciding with Congress' failure to pass a legalization bill and the Bush administration's stepped up raids and enforcement.

In a study released Thursday, the Pew Hispanic Center estimates the illegal immigrant population fell by 500,000 from 12.4 million in March 2007 to 11.9 million this year.

The study's authors caution that the finding is "inconclusive" because of the margin of error of the estimates, though the findings mirror those of the Center for Immigration Studies, which also estimated a drop in illegal immigration.

The Pew study says there could be many reasons for the drop: a slowdown in U.S. economic growth that has dried up opportunities for illegal workers, economic growth in Latin American countries that has kept some workers at home, and heightened enforcement in the U.S...

Ginger Thompson of the New York Times has a similar story here. Note that the NYT has acknowledged that attrition would work, they've just falsely tried to claim that it would be inhumane.