Today's New York Times has a sad story on how illegal immigrants are contributing to Social Security through automatic payroll deductions. Since they're working illegally, using false social security numbers, they don't expect to collect. [Illegal Immigrants Are Bolstering Social Security With Billions, by Eduardo Porter]
Porter doesn't discuss the enormous cost of illegal immigration: health, education, crime, et cetera, and he doesn't seem to know about the possibility of totalization agreements, which will pay billions and billions of dollars in social security to Mexicans who have gone home to retire.
Update: For a technical analysis, proving conclusively that immigrants can't save social security, see Ed Rubenstein's March 24 piece on the numbers involved. If you think Eduardo Porter's piece was one-sided, you might want to contact the Times Public Editor, Daniel Okrent, firstname.lastname@example.org. Good luck getting any satisfaction out of Mr. Okrent, though.