Uh-oh. Every so often you lose what you thought was a perfectly good reason to flame someone (so a petty, geeky distinction not worth pointing out), like this one:

Because of a problem with copyright infringement, Apple didn't think it could keep the Macintosh name, already in use by another company (though with the correct spelling, 'McIntosh'). It experimented with MAC (Mouse Activated Computer, reverse engineered from Macintosh), Apple IV, Bicycle (Jobs' favorite), and Esprit. None sounded right, so Apple instead paid a hefty fee to obtain the name 'Macintosh', as it did with the name 'Apple' itself some years later. (emphasis mine, of course)

Well, it seems that all those people who say MAC all this time aren't nearly as wrong as they might have seemed. Even if they stumbled into the non-mistake, you have to admit (if this page is in the right), there is a historical basis for them using "MAC" to mean Macintosh. Dang! ;^)