According to a report published by Asymco iPod Touch possesses about 37.7% share of all the iOS devices sold. The number they have given about the total number of iPod Touches sold is 45.2 million. They have also noted that if the sales of the iPad continue as they are at the moment then the non cellular devices will take upto 50% of the total iOS devices share (other 50% for of course for the iPhone).
We should also note that iPod Touch now has a Facetime feature that would definitely boost its sales and also other features such as long awaited camera and the retina display has also been added to it.