Ira Mehlman of FAIR reports on some of the details of the immigration-related measures attached to the Iraq funding supplemental, bringing out the numbers that may be involved in these amendments. He thinks at least 2 million individuals could have their statuses changed:

In one afternoon, the Appropriations Committee approved amnesty for 1.35 million illegal alien agricultural workers, and made available an additional 650,000 skilled and unskilled foreign guest workers over the next three years.
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The 2 million figure does not include the dependents of the amnesty recipients or new workers who could be admitted under existing agricultural guest worker programs. Under the agricultural amnesty – written by Sen. Dianne Feinstein (D-Calif.) at the behest of the California agricultural lobby – the spouses of amnesty recipients will also be authorized to compete with American workers for jobs in any sector of our labor market. Nor does it include the potentially unlimited number of new guest workers agricultural employers will be able to import under a “streamlined” H-2A program that requires the Department of Labor to issue visas within seven days of an employer’s request.

In addition to Feinstein/Craig, other immigration measures were tacked on to the Iraq supplemental for both "skilled" and "unskilled" workers (e.a.):

The Maryland fishing and tourism industries also want a ready supply of cheap foreign labor, and Senator Barbara Mikulski (D-Md.) was happy to accommodate by offering an amendment that exempts returning unskilled or low-skilled H-2B workers from counting against the caps for that category. (Never mind that there are fewer Maryland crabs to harvest each year, and that with the skyrocketing price of gas people may not be able to afford to drive to the Eastern Shore.) Over the next three years, the cumulative number of H-2B workers admitted could reach 432,000.

And while the Appropriations Committee was piling on goodies for the low-skill industries, they found time to take care of the lobbyists for the high tech industry as well. Sen. Patty Murray (D-Microsoft/Wash.) added a provision to “recapture” 218,000 visas for skilled foreign workers. These visas didn’t really “escape,” so much as they just went unutilized between 1996 and 2004, especially during the years immediately after the high tech bubble burst. But now high tech employers and labor contractors want those visas back, because foreign guest workers tamp down labor costs for the industry.