Foreign-born members of the military can apply for US citizenship without the mandatory five-year waiting period. In general, when the foreign born apply for citizenship, there is a five-year waiting period from the time they get their "green cards" until they can apply to become naturalized US citizens.
Under previous rules, the five-year period was reduced to three years for military members. Since a July 3, 2002 executive order, there has been no mandatory waiting period for military personnel. The naturalization process typically takes eight to 10 months from the time an application is submitted until the oath of citizenship is administered.
Even though this policy has been in effect for a few years, I can't help but see how this will play into the whole immigration debate here. We crack down on illegal immigrants and threaten to send them back to their native countries, but then not-so-subtly hint that they could become instant citizens if they would just sign up for a stint in the military. Voila - we've fixed the problem of low recruitment numbers without a draft. And, since according to the story, of the more than 2,400 U.S casualities in Iraq since 2003, 270 have been Latino, we might not have to worry about them stealing our jobs when/if they return.