Take me as an example. I have paid in $69,058 as of 1/1/2011. Assume I could request a check for that amount right now and not collect Social Security at retirement.
If I live to 75 (male life expectancy from wiki) and retire at 62. I would receive $828 every month for 156 months from Social Security. That is $129,168.
The government saves $60,110.
Over the next 20 years, 74 million boomers will retire. If my situation is "typical" the government could save $4.45 trillion!