Seriously, though, this has irritated me since the days where dialup internet access was all a normal person could get. All these plans were "unlimited", but in the TOS they made it clear that if you tried to use the service too much, or tried to stay connected too long, you're account would be suspended or closed.
Something is either unlimited or it isn't. If there's a cap it isn't unlimited. I guess I might cut them some slack if they described it as "effectively unlimited" (meaning that there was more bandwidth than an everyday person could expect to use). Of course, on many services that have been labeled "unlimited", even that would be arguable.
Of course, I don't expect most people in advertising to be honest about anything (goods/services are usually described as a hundred times better than they could possibly be), but that doesn't mean I'm not still annoyed by it.