Listings have been running higher because the price sellers think they can get is inflated. In addition to low interest rates the market improved in 2009 because sellers understood that they needed fairly substantial discounts off peak price and buyers could find better value (relatively).
It no surprise that listings have increased as asking prices have. Consider a benchmark house I have previously covered. Approximately 1700 sqft 2-story house with double attached garage and bonus room in a newer south east Edmonton community of Ellerslie. In October 2009 I did a comparison of one that was priced at $374,900. I noted that the price to rent ratio was high at 220, but with the financing available at the time the buy vs. rent was closer.
Now the least expensive house that matches the same criteria is this $410,900 1701sqft two story. In this environment people are coming out of the woodwork to sell.
There are other similar houses asking more. Asking prices in general will need to fall to move the inventory that is accumulating.