Some areas definitely have more stock than others. I read an article about how some parts of the country were completely sold out of both systems while large amounts of them were sitting unsold in places like New York. My guess is that this week supply will start to spread out more evenly and seeing them on the shelves should be common.
MS had said early on that they were planning on delivering very large quantities as well as not preselling the entire initial shipment because as they said early on that they wanted extra for people that may not have preordered in advance but wanted a shot at getting one. The fact that that you can find them on the shelves has more to say about MS's ability to manufacture them and less about demand.
I don't think people should look to much into it. Both systems are selling very well, in spite of disjointed demand in some countries. Also, both systems have outpaced the adoption rates of their own predecessors and should each enjoy a healthy share of the console gaming community in total.