Ruthie -- the game was first released via download in 2007. Now it's being released in a boxed version in North America (you'll see it on store shelves).
Release dates are something of a "guess." Sometimes, even when the game is effectively a year old, there are holdups with copying the disks or with the box itself or with the shipping. Sometimes one part of North America gets the game on store shelves a couple of weeks earlier than another part. Sometime the game shows up at Circuit City, but it takes three weeks for it to show up at Best Busy, (I mean Best Buy) or vice versa.
So release dates are approximate, just because of the nature of the production and shipping process, if you know what I mean.