""Visually. it seems to exceed the decline in May-Jun 2010""
That's an interesting observation because I made a similar one while looking at equity charts yesterday: this current drop is very strong and exceeded only by last July-August's debt-ceiling-fiasco drop.
Also, while stochastics say the market is "oversold", it can stay "oversold" for some time (just as it can stay "overbought"). IMHO the Bollinger Bands are key: as long as the price doesn't stray outside the BBs, they can continue walking the bands (in this case downwards) for a long way.
Remember that "the financials lead"... and right now that seems to be very much the case. I'm watching the financials for potential reversals.
Last, candle charting says that normally we have up to ten candles of the same color and/or moving in the same direction. A few equities (GS, for example) seem to be reaching their 10, but some had a bit of a bounce and have had 4-5 down candles.