Just think how would you feel if the Rails or Django guys decided to take everything down. You have the full commit history, if you had cloned the Github repo, so why do you care?
That was the page I learned my first bits of Ruby on. That was the page I introduced 8 friends to Ruby for the first time. It was the page I single-handedly got our contract renewed, by proving a piece of functionality was possible and easily done.
I think for many, it was an easy way in to Ruby. Someone must replace this immediately.
One of the things that bother me more is the fact that he also pulled the plug on all the mailing list of his projects, which would have been the right place to discuss what to do with the code.
My wife actually noticed yesterday that it was gone before I got around to reading all the comments on HN about Why's departure. I eventually told her that he was basically dead. Her response? "How am I going to learn Ruby now?"
I of course have installed a local interpreter, but she really liked the lessons.