For the longest period of time the classic proxy for the theoretical risk-free rate has been the 3-Month U.S. Treasury Bill, this may have to be re-thought given the U.S. debt-crisis that just got "resolved" today. The crisis brought home the realization that the U.S. Ecoomy, far from being infallible, is actually vulnerable in it's present state.
The longer-term ramifications of both the crisis itself and the solution that was agreed upon today are going to be profound. The United States has re-discover its place in the global economy instead of relying on past laurels, and soon, while the other developed nations still look to it for economic leadership and haven't realized that this need is more psychological than anything else...
