President Bush's immigration policy is pure genius. Illegal workers who are already in the U.S. can accept his plea bargain, register themselves, pay a fine, register their families and their employers with the federal government, and in return they get a 3 year work visa.
Then, after investing 3 years of their lives in this work program, they have to deport themselves back to their home country in order to apply for a blue card extension, green card, or re-entry permit.
If they don't self-deport, then we know where they live because they are registered (something that prior to Bush's plan they were not). We know who their employer was so we can apply pressure there, too. Plus, they lose the taxes that they paid in to our system (some of which are refundable to them if they play by Bush's rules and self-deport). Moreover, after registering, their employers have to pay U.S. wages and payroll taxes.
So in 3 years we don't have to bring in the military to round up 8 million people in some vast chain gang march back to Mexico. Nope, now they have to deport themselves or else risk losing their paid in taxes, their chance to ever be legal in the U.S., as well as lose their job (because the new change that makes this different from the past is that Bush is registering these illegals so that we finally know where they are living and working).