It briefly crossed the 200€ mark yesterday. Maybe a lot of people wanted to cash out at that point. As soon as the price was dropping, more people decided it was a good time to sell.
While it was dropping, there were two ways you could expect it to go. Either it was dropping and was going to stay low, in which case you should sell, or it would rise back up in which case you should sell and then buy when it got cheap.
Mtgox the exchange (not Bitcointalk the forum) is under DDoS which caused the panic selling.