The military branch uses a network of around 2,000 PlayStation 3 units running Linux for research, a structure which proved to be more affordable thanks to Sony's hardware subsidy. The setup isn't in any immediate trouble, as the consoles aren't hooked up to PSN and don't need to be updated, but when the units die out it will be difficult -- if not impossible -- to replace them. Considering they just constructed the rig a few months ago, the Air Force has expressed disappointment. And as you'll read in the Ars story, Uncle Sam isn't alone in his frustration.
Oh, and sorry about the lack of Top Gun references in this post, but that's actually a movie about the Navy. We know, we were disappointed too.