http://www.pcgamer.com/2010/10/11/blizzard-bans-starcraft-2-single-player-cheaters/

So Blizzard is banning players who cheat in Single player.

Good move Blizzard, I hope it happens to D3 as well. QQ cheaters.

We are not banning players for using single-player cheats.

The confusion all comes from an inaccurate statement that we think cheating in single player negatively affects achievements or some such. Not the case. I don't even know if the person who this story is based on actually got banned, but if they did, it's because they were using a hack inside a multiplayer game.

I would recommend that if you want to cheat in single player StarCraft II games, use the ones we put in there. A lot of the hacks out there work in both single and multi. If you get a third party hack and intend to only use it for single player, and then go play a mutiplayer game with it still on, you're bound to get tagged.