I was at Walmart this weekend and saw at least three Wii Us on the shelf. It was hard to tell if more were stacked behind them, but there could have been. For all I know there could have been a pallet of them in the back. They were all the white ones, I didn't see any black. The store didn't have a demo kiosk set up for the Wii U which I though was strange. When I left the department there was a guy buying a Halo 4 Xbox 360 bundle and a woman buying a PSP. Not a Vita, but a PSP. I was buying some rechargeable batteries so I didn't have to make the purchase in the electronics area, but there was a kid with her parents that I heard say something about Nintendo. Maybe she was bringing them in for a Wii U.
There was one item sold out completely. The 3DS shelf didn't have any regular or XL boxes. That thing seems to be doing very well.
