There are more than 24 million USD worth of bids at MtGox. There were only 12 million USD in bids a few weeks ago.
Doesn't that also mean there's twice as many sellers as last week? I.e. people wanting to cash out.
More than one million USD worth of other currencies (mainly JPY) are leaving MtGox every day, and I assume some people are depositing as well.
There are many more deposits coming in than withdrawals out. A lot of people want to cash out at $400 or $500, but they can't, at least not on Mt.Gox, since it would take 8 weeks of uncertainty. So they cancel withdrawals and move BTC elsewhere. Bitstamp, Coindesk etc. Soon there's going to be an exodus to exchanges, wherever people can convert to USD/EUR.