Fannie Mae's Debt Issue & Credit Yield Spreads

Amid speculation that Fannie Mae doesn't have enough capital to weather the continuing credit crisis, it has gone ahead and issued $3 billion in new debt. What's interesting about this, however, is the yield (cost) at which it was issued. The new debt will yield 3.25% - a full 74 basis points above the equivalent U.S. Treasuries. Given that Fannie Mae, theoretically, has the backing of the U.S. government and, consequently, should benefit from essentially risk-free cost of capital, this suggests the investing community feels otherwise about its credit worthiness.

With all the talk about the ratings agencies and the validity of those ratings, I suppose it's not all that surprising to see investors making their own determinations about the credit risk associated with a particular issue. Moreover, when you think about it, shouldn't the market as a whole be better qualified to determine the risk associated with a particular security than a single ratings agency?

The capital markets serve as a pricing mechanism. The collective buying and selling of millions of investors every day works to determine the value that we, on average, associate to a particular security. Why, then, should we not use the power of the same distributed intelligence to ascertain the credit risk associated with a debt issue? To be fair, the markets already do this - using the ratings agencies as a sort of starting-point for their evaluation. My question, I suppose, is whether or not we actually need that starting-point.