I said I might comment on this at some point, and now (as I monitor the temperature of a He-3 probe and not much else) might be as good a time as any. I'm not an expert on the subject, only having read a few articles, some positive, some negative. I am somewhat biased in the matter, as two of my grandparents are immigrants, so I am, broadly speaking, pro-immigration. Pro-immigration doesn't mean pro-illegal immigration, however. I'll admit that I've never given detailed thought to the matter before, but whenever faced with the problem of illegal immigration, my first instinct is enforce immigration laws, but make legal immigration easier.
So let's look at the Bush proposal for what it is and what it is not. It's not a straightforward amnesty, although it does deal lightly with current illegal immigrants. They would only have to pay a fine before they could join the program. The important point, however, is that when they joined the program, they would not be given green cards and a quick path to US citizenship. They would instead be classified as guest workers, who could stay in the US for a limited duration of employment, and would have to apply through the normal channels to become US citizens. The program is not intended as a means of exploiting workers, since, by keeping track of the workers and their employers, it could enforce minimal benefits for them, including minimum wage, health and safety standards, and taxation. One of the things that peeves many of those who oppose the plan is talk of "jobs Americans will not do." They make the legitimate point that with the right wages and benefits, Americans will do the jobs. That is certainly true, but I would point out that with the program in place, the cost benefit of hiring cheap migrant workers will be decreased, to zero as opposed to hiring an American worker at minimum wage and benefits. Thus there will be less demand for foreign workers if there is indeed a ready supply of American labor for the job.
There is a very legitimate concern here. What about those who don't sign onto the plan? Businesses who want the cheapest possible labor, which can only be had sans the legal worker protections, and workers who can't get into the beneficial plan. There will still be a demand and supply of illegal labor. The question then becomes whether it is more possible, and there exists a greater political will, to enforce the new immigration plan than the old immigration plan. That is a question I don't have an answer to.
As you can see, I'm not arguing strongly for this plan. I think it is reasonable, however, and worth discussing, and I'm tired of hearing critics say the plan is mercenary political pandering. It was clear when he was elected that Bush was a moderate, and while he didn't push this particular plan, he made it clear that he was pro-immigration and seeking a compromise solution to illegal Mexican immigration. Moreover, there's plenty of evidence that Bush's views on Mexican immigrants are consistent with his Texan outlook and that he personally has a lot of empathy for the Hispanic community, especially given his behavior in this low-publicity visit.