It appears that the newest anti-multiboxing rallying cry is to claim that key broadcasting, particularly via programs such as keyclone, are automation, and therefore a ToS violation. The premise is that you're using one keypress to "do the job of many" keypresses. In Vyndree's thread on clarification of semantics (ironically enough) one poster tried to use the following definition:

Add in a 3rd party program. You press ONE button and all 5 screens react. How exactly is that fair/legit? It's not. The ability to control 5 computers at once with 1 single keyboard and 1 single press of a button is automation. The ability to make your characters cast their individual spells and skills at once by pressing 1 button is automation.

1. the technique, method, or system of operating or controlling a process by highly automatic means, as by electronic devices, reducing human intervention to a minimum.
What has Blizzard stated regarding automation? From that same thread:

"Unlike the forms of botting you mentioned, multi-boxing requires user input and does not automate any aspect of gameplay. Each time an action is performed it is controlled by a real player sitting at their computer controlling multiple accounts. "
Aradek, Customer Service Member
"Is it sending an identical signal to all client windows or switching between them to send commands? Not automation.
Is it playing the game for you, or rather, for one of your client windows? Automation."
Belfaire, Blizzard Poster
Since people want to insert or invent their own definitions of what automation means, (or apply the wrong definition) the above responses make it clear. When Blizzard refers to automation, they are referring to automating actions within the game by means not available via the standard interface and macro system.

What does this mean? It means that the external means that you use-- be it a keyboard, mouse, multiplexer, keyclone, etc-- as long as it sends a single keypress/button click to a single instance of WoW at a time, is NOT AUTOMATION. If this was automation, then the in-game macro system itself would be a violation of the Terms of Service, since you can use a macro to combine keypresses (example, have it activate a trinket and then perform an ability or spell).

I repeat, any external means of directing input to an instance of WoW that does not automate actions within the game is NOT a ToS violation. So if you send a keypress to 100 instances of WoW and each of those instances receives that single keypress... it isn't a ToS violation. Don't get sidetracked by people who have basically found a new way to say "I don't care what Blizzard says, I make the rules!!!" They are going to try to argue the semantics of "automation" until their lips fall off, but because their premise is flawed, so are any of their arguments. Once you strip their arguments away, they will fall back on stating directly that "I don't care what Blizzard says, it's illegal!"

And at that point they can be safely ignored. Once they get to that point, they are practically admitting that they have run out of ways to try and make facts and logic fit their opinion, instead of the other way around.

Now to wait and see what new tactic they come up with...