Market strength, Bitcoin/USD, TradeHill, Current.
There are a lot more people trying to sell Bitcoins than there were 8 hours ago. But they're trying to get $17 or so, which isn't happening.
There's less buy-side strength than there was 8 hours ago. The buyers who wanted to buy have bought. Right now, buying 1000 Bitcoins at market would only move the price up $0.25, but selling 1000 Bitcoins at market would move it down by about $2.
So after all the noise, we're back to around $15, just like the last three days. That seems to be the new normal.