If it was a bank run, the volume at other exchanges would equal that of MtGox because people were buying on MtGox to sell on other exchanges.  But it isn't.  Not even close.  Volume on MtGox today is much higher than on other exchanges.  USD volume alone is more than 3x the volume on Bitstamp, and 4x when you add up the rest of the currencies on MtGox.  No signs of empty hot wallet on MtGox today either, so probably just a normal rally where MtGox is leading as usual.