History shows that anytime one of the exchanges goes down, usually due to hacking, the value of a Bitcoin drops significantly. This time around, the site is closing intentionally, but it looks like it may be having the same impact.
I received an email notice from ExchB at precisely the time that the significant drop started, just over an hour ago. The price at the time was $3.72. It is now $3.39. The last time the price was that low was on May 7th!
UPDATE: $3.01. Crazy.