There are three more charts in addition to the SPYs that should cause concern.
Financials comprise 20% of the S&P 500. The last week of trading has really taken of toll on this sector. Today it closed below it's 200 day SMA. Also note that volume has been heavy the last three days, indicating traders are getting out of the sector largely because of the issues in the subprime market. Because this sector is such a large portion of the S&P, this will really impair the S&P 500s ability to rally.
Energy and basic materials have been an important ingredient in the latest rally. Notice the energy ETFs closed below their 20 day SMA with a strong downward moving bar and pretty heavy volume.
Notice that basic materials closed below their 50 day SMA on very large volume.
So we have the S&P and three of its most important sectors in a bad place right now.