Bitcoincharts now show okcoin to have the highest trade volume:
http://bitcoincharts.com/charts/volumepie/I guess, it's possible if they have 0% fees, but is there a way to tell if it's another Willie doing that?
Part of it should be related to the 0% fee, but I doubt it is the only cause of it.
Probably there is a "Willy" bot, or probably the exchange just fakes the figures.