It's funny that you should mention the MIT sense of the term. I was very influenced by this line from The New Hacker's Dictionary, which came out of the MIT hacking culture:

"[T]he ties many hackers have to AI research and SF literature may have helped them to develop an idea of personhood that is inclusive rather than exclusive — after all, if one's imagination readily grants full human rights to future AI programs, robots, dolphins, and extraterrestrial aliens, mere color and gender can't seem very important any more."

It has been a rather rude awakening to realize how much hacker culture is the opposite of that. They see the most powerful and intelligent people as looking like themselves, and see their exclusion of anybody else as proof that they were right about it. They believe in a "meritocracy", but define themselves what constitutes "merit", and it just happens to be the things that they're already doing.

I don't know what's actually going on in Cambridge, Mass, but Hacker News brings me every day evidence from their successors in Silicon Valley. I see so much intolerance here.