Good point.I tend to think the terse, one line responses come from him, because they sound like something someone would hammer out on theirblackberryiPhone while it's hot on their mind.
I am sure that he has a small and trusted staff that handles his routine e-mail for him.Although I wouldn't put it past Apple to actually train the assistants / whoever who actually do most of the responses to be terse like Jobs so that it seems authentic. Actually, I wouldn't put it past Apple to hire a bunch of FSJ's and make them wear those god-awful black turtlenecks and jeans from the 80s.