I am in the UK and I have not seen a big increase in the number of wiis in the shops.
I have been looking for a wii for about 2 weeks. I have been looking on the internet mostly, the only site I have found with a good number of wiis in stock is from a company called GAME. They are not sell out as fast as others because the cheapest wii they sell is £310 in a bundle with 4 games. They don't sell a wii on its own anymore which costs £180.
I am trying to get a wii from amazon at the moment. They are one of few retailers that still offer the wii on its own (not part of a bundle). They have been getting a small but steady flow of wiis. They have been adding 2 wiis at a time to their site at random times of the day.
I have even gone as far as to write a computer program that checks amazon's site about every 20 seconds to see if they have wiis in stock.