President Bush has released some details of his proposed immigration reform package (here's my reaction to the initial announcement), and maybe I'm obtuse but I don't see how these reforms would be any different than current work-visa programs. Except, of course, that currently-illegal aliens would be able to apply, whereas they can't apply for visas.
I'm not sure how much of an effect these changes would even have (which is good enough reason to oppose them -- pointless laws are bad). Illegal aliens who register would then be subject to deportation after a few years, and we'd know they're here, so how many do you really think will sign up?
One of the biggest flaws I can see is that the system would require employers to "show no Americans wanted the jobs being applied for" -- this requirement belies a staggering ignorance of basic economics. Americans will do any job, for the right price. If no one wants a job, that means you aren't offering enough money. This new rule sounds like it would allow companies to offer jobs for unrealistically low wages, and then import workers from other countries to fill the purposefully vacant positions.
Foreigners would obviously leap at the opportunity to come to America legally, no matter what job they're offered or what the pay is. No nuclear engineers are willing to work for minimum wage? Just get on the phone with India or Pakistan and bring 'em over by the boatload.