Workers have been paying higher social security taxes than necessary for 30 years. In 1983,

[Starfury]

38. And the Trust Fund earns interest

I don't believe I've ever heard mentioned in these sorts of discussions, but not only is there currently a huge surplus, it earns interest. From How Social Security Trust Funds earn interest:

By law, the assets of the Social Security programs must be invested in interest-bearing government securities or securities guaranteed by the government. The Trust Funds hold a mix of short-term and long-term government securities. The Trust Funds can hold both regular Treasury securities and special obligation securities issued only to federal trust funds. Currently, all securities in the Social Security Trust Funds are special obligations.

The rate of interest on special issues is determined by a formula enacted in 1960. The rate is determined at the end of each month and applies to new investments in the following month.

The average of the 12 monthly interest rates for 2010 was 2.760 percent. The effective interest rate (the average rate of return on all investments) for the OASI and DI Trust Funds, combined, was 4.6 percent in 2010. This higher effective rate resulted because the funds hold special-issue bonds acquired in past years when interest rates were higher.

I read elsewhere that the effective interest rate for 2011 was 4.4%. Not too shabby in the current investment climate...