Maybe they are intentionally driving down the gold so they can buy it all up at a cheaper rate......
The one guess that I've heard, that makes the most sense to me right now, is that the central banks of the peripheral EU nations (maybe Cyprus, Spain, Italy, Slovenia, etc.) might possibly be looking to liquidate their gold reserves as a means of 1) doing a self-bail-out so as not to get Cyprus-raped by the Germans, and 2) exerting some kind of monetary and financial independence from the core EU nations (in some ways the same thing as #1). Again, this is all speculation at this point.