Recent StarCraft II Account Suspensions
We recently issued a new round of account suspensions and bans to StarCraft II players who were in violation of the Battle.net Terms of Use for cheating and/or using hack programs while playing. In addition to undermining the spirit of fair competition that’s essential to play on Battle.net, cheating and hacking can lead to stability and performance issues with the service.
As always, maintaining a stable, safe, and secure online-gaming experience for legitimate players is a top priority for us, and we'll be continuing to keep watch on Battle.net and take action as needed.

I remember a game where a kid (had to be a kid or a very immature player) told me "I hack so don't try to do win over me!" It was very funny to kick is ... with my zealots! I didn't knew at that time that hacking was possible on SCII :(
he also goes around killing everyone in coops.
I suspect that Blizzard is more likely to let more offenders free than to punish innocents. The level of bad feelings from customers is reduced that way.
(and don't smoke)ROTFLCOPTER
What's pay2use or external hacks. I'm not familiar
There's a bunch of stuff on it, just Google it. If you need a link though. http://www.cnn.com/video/data/2.0/video/bestoftv/2011/04/27/exp.mxp.playstation.hackers.hln.html
I have been watching my replays a lot recently and have had two games where the other player does a beeline straight to your base when you are at diagonals on a really big map. I studied the replays and could not see them looking at dark but my guess is that they had some sort of hack going. Good to see blizzard getting rid of this kind of thing that only ruins the game.
PS: study your replays after you matches there are still alot of hackers out there man.