I wonder if they're test-marketing them. Around here, we get candy bars and cereals and such that you don't see in other markets (sometimes ever, sometimes until much later), and this might be yet another thing/idea being tested. Just a thought.
I know around here they've done 8-packs of bottles, 8-packs of cans, 10-packs of 8 ounce bottles and cans. Seems like every permutation on containers possible.