Obviously a lot of speculators had jumped back on the Gold train buoyed by two strong bullish signals; technical support around $1525 getting truely tested but surviving, and talk of further QE from the Federal Reserve.
Mr Bernanke did not add any fuel to the QE fire in his speech last night, so this seriously dampened the bulls enthusiasm and sent many chasing to the exits, with Gold falling by $30 very quickly. Other commodities suffered similar experiences and this of course showed up in the FX markets in AUD volatility.