I'll use Black Ops as an example, as it is a popular upcoming game in both countries. At the moment, the Australian dollar is worth more than the US dollar, but they are practically the same, so for the sake of comparison assume they are exactly the same.
At Gamestop, what I understand is the main games retailer in the US, http://www.gamestop.com/Catalog/ProductDetails.aspx?product_id=77793
At EB Games, the main retailer in Australia, http://www.ebgames.com.au/sale-product-663-home-Call-of-Duty-Black-Ops
That is double the price. Are we simply getting ripped off by greedy companies, is there some reason for games to cost more here, or...?