Surest sign of a massive short squeeze underway is when pharmakablooie or whateverthef*** he calls himself shows up and) turns on his spam machine. (check out his history, and compare w/charts. It's hilarious.
I'm not sure exactly what's going on, but based on the volume right now it looks like a couple of hedge funds are trying to flood the market with newly shorted shares in an attempt to cover their older shares lower. That's just a guess. But after 9 million shares trading hands, they still can't get this price to capitulate below the $4.60 range on a sustainable basis, so I would not be surprised to see a big uptick before the end of the day as some of these shares cover.