I've also been hunting for the boxed copy, since I love the mods that usually come out for ArmA, and knowing that the steam issue had serious issues with running the mods...if at all, I would prefer the boxed copy.
However I've not been able to locate the game. Gamestop confirmed to me that they pulled the game and will not be releasing it, and the only place, as mentioned by the above poster, that has heard of the game is Best Buy.
I just got off the phone with Best Buy about a half an hour ago and they said that the game is available on the site, however the site says backordered. I asked her if she knew when the stores would be getting it on the shelves and she stated that she was unsure, and that the system did not have a set date. She told me that it could arrive in any shipment at any time and to keep checking in.
So, yes, Best Buy has and will carry the game, the question is simply when they will, not if.
It's been kind of an interesting hunt, though. If I come upon anything for our US players I will be sure to post something up for you guys.
As for different shops, sadly in the US we're quite limited. Especially for someone like me, who lives on the middle of no where in the state of Ohio, we really rely only on the larger retailers out here to supply the game. Best Buy and Gamestop are the only choices for me. (Circuit City is gone, and Office Max and Staples out here no longer carries games.)