The Wii's YTD lead ahead of the PS3 is only 10k now. PS3 will probably edge ahead within the coming month.
Two weeks max - however, the Wii is getting a few big titles soon which could tip the scale temporarily. It will be interesting to see if the Move matters at all for Japan, but that'll have to wait until October 21st if I remember correctly. Between then and now they could have traded places a few times already.