Pfchang, it is my understanding that the only trades which were busted were those where the trades were more than 60% off the final price of the day. Thus, the one cent trades for Accenture and the firm which makes Samuel Adams beer were cancelled but the $39 trade for PG and the $199 trade on AAPL stood.
It really makes you think twice about using stop loss orders. Imagine, Apple was trading around $247 and you get stopped out at $199! Same thing on Proctor & Gamble -- it was trading around $61 per share and you get stopped out at $39, all in a matter of a couple of miinutes and then both stocks return to their previous levels.
Stuff like that might even convince the GOP that markets don't always take care of themselves and the public could use a little regulatory protection.