A load of btc were dumped onto the market, but there hasn't been a fundamental failure in BTC to cause it - the rise itself didn't really make a lot of sense, either. If anything, I suspect this is another ploy to get you to sell your btc cheaper so someone else can buy up big.
Er is mt gox having a spaz attack? I just saw it hit $7 again...then back to $6 as if it never happened...