In response to Jerry: I don't take a great deal of exception with most of what you say. I do, however, take issue with the idea that the banning of shorts in certain securities was the responsible thing to do in the current environment. If anything the markets should have just been closed for as many days as it took the SEC & Congress to figure out what they wished to do about this "crisis of confidence" (the most likely course of action will of course be a trillion dollar ,government funded, waste basket used to absorb bad assets and allow brokers to de-lever). Closing the US stock market is hardly unprecedented. Instead, the government chose to rip-the-face-off (that's a technical term) of many legitimate alternative investment managers who had fundamental long and short positions in place. It is a gross and irresponsible redistribution of wealth from hedge fund investors (the largest of which are pensions) to long-only fund investors (the largest of which are pensions).
It may also have been an outright attempt to manipulate the stock market higher in order to provide the volume needed to liquidate the ~$800bn in Lehman assets that need to be sold.
The ability to sell stock short did not create massive amounts of leverage on tiny pools of capital and temporarily banning it won't fix that root problem either.