It's a fools rally based on the Fed's last-ditch efforts to avoid a systemic financial collapse. I can't imagine a more clear sell signal than this.
Free capital gains means I (and others) would just double-down on our shorts. It would crash the market in no time.
Now, double the capital gains on shorts/puts and eliminate it for long positions? That might do something.
It's a rally based on emotions, just like the past couple of days of crashes are emotions based as folks try to sort out the credit crunch mess. Expect huge swings either way.