UPDATE (8:52PM ET):
Futures are off of there lows.  But they're still low.
Dow futures are down 182 points, and S&P futures are down 19 points.
Here's a look at Dow futures via FinViz:
futures
UPDATE (8:22 PM ET):
The sell-off is accelerating. Dow futures are now down 250. S&P futures are down 25 points.