Basically if Blizzard decide any commonly used piece of third party software is a breach of EULA or TOS they can ban its use and its users.

Really you have to look at potentials, a basic maximiser program does only one thing, its doesn't actually effect how you play the game, it does nothing that you can't do your self (okay maybe something you can't do...), it just makes things easier. 99% of the people who use I would imagine don't even dual/multi-box.

Looking at AHK I would think the odds are quite high that at some point it will come to mainstream attention, and that Blizzard will ban its use, I first came accross it while looking for EVE mining macros, I know there are runescape macros, and I have heard of a good WoW fishing macro. All these are designed to avoid repetetive tasks in the games. Which is pretty much the definition of AFK playing.

The fact that I would think most of the people who use it on these forums are using it to send single keypresses to multiple clients is not really an issue. If its added to Warden to be detected anyone using it can be banned, and looking at places like the Glider forums, Blizzard don't generally accept excuses, by the time you get banned they know enough about your playing habits to know if it was a mistake that the software was running or not.

Keyclone, Synergy, Multibox, etc... Personally I would imagine that theses are in the same boat as Maximiser, they do a single thing they allow one person to send input to more than one client, be that several clients on one PC or several PCs each running a single client (or many other arrangements) what none of them do is allow automation, though with enough programming skills either Synergy or Mulibox could be modded I'd imagine. Luckily, and I think by intention, Keyclone is closed source and so if likely free from such ideas.

Bottom line as I see it from the software that is banned, any third party program that is intended to modify the client or the data it sends/recieves from the server is banned; any program that allows interfacing directly with the client at the API level is banned (inner space?); and any program that automates your actions dependent on what the client is doing, either through monitoring memory values or through color matching (fishing bots) are banned.

Of course there are others, but you get the gist. Blizzard are trying, with some success, to create a level playing field. While some may say that dual or more boxing breaks that paradigm, they would be wrong. Ask any 5x boxer what happens when people who are prepared to die attack their group, A phsycic Scream (?) in the middle perhaps? It might take another group several tries but even Xzin is not unbeatable (allegedly ). A level playing field by Blizzard's terms is a playing field that doesn't include the use of bots, hacks, cheats and exploits.

Though arguably they seem happy to turn a blind eye to gold sellers, advertisers and buyers.