Alabama is shaping up to be a test case on this issue. So far, it's looking like what was in the Times article was not fishy at all:

Why Americans Won't Do Dirty Jobs

By Elizabeth Dwoskin, Business Week,  November 9, 2011

In the wake of an immigrant exodus, Alabama has jobs. Trouble is, Americans don't want them

The article starts out talking about catfish cleaning work, but it is mostly about farm labor and farmers screaming bloody murder about the new Alabama law.

I found these grapsh in it particularly interesting:

....The notion of jobs in fields and food plants as “immigrant work” is relatively new. As late as the 1940s, most farm labor in Alabama and elsewhere was done by Americans. During World War II the U.S. signed an agreement with Mexico to import temporary workers to ease labor shortages. Four and a half million Mexican guest workers crossed the border. At first most went to farms and orchards in California; by the program’s completion in 1964 they were working in almost every state. Many braceros—the term translates to “strong-arm,” as in someone who works with his arms—were granted green cards, became permanent residents, and continued to work in agriculture. Native-born Americans never returned to the fields. “Agricultural labor is basically 100 percent an immigrant job category,” says Princeton University sociologist Doug Massey, who studies population migration. “Once an occupational category becomes dominated by immigrants, it becomes very difficult to erase the stigma.”

Massey says Americans didn’t turn away from the work merely because it was hard or because of the pay but because they had come to think of it as beneath them. “It doesn’t have anything to do with the job itself,” he says. In other countries, citizens refuse to take jobs that Americans compete for. In Europe, Massey says, “auto manufacturing is an immigrant job category. Whereas in the States, it’s a native category.”

In Alabama, the transition to immigrant labor happened slowly....