I hadn't heard anything about that at BlizzCon even while playing the sexy Starcraft II, but considering it'll only be for the campaigns and the actual multiplayer and battle.net play should be accessible from any of the games it's really not that bad.
If you just want to play online you just get one box, same as always. If you want the extra stories, you'll get two or three. Kind of sucks that you have to pay 2-3 times as much, but each campaign will be longer than all of the original campaigns put together it says, so I can see how it would be worth it to those interested.