shipping dates are what get listed, not actual release dates (which vary from store to store). Add 1 day for video game stores like Funcoland, babbages, EB World, Software etc, or even Saturday matinee. Add at least 2 days for CompUSA, Best Buy, Circuit Cities and the like. Add even more for chain stores like Walmart that don't specifically cater to any one type of product.
Some really good stores in more urbanized areas (like where I live) will even get the shipments on the evening of the shipping day (by sending a manager to UPS/FEDEX and picking it up themselves.)