I'm all for leadership by example. I think that Joel led by example when he was still actively developing code.
Hanging blinds? Not so much. Hanging blinds strikes me more as an entertaining diversion from normal work than as a way to show leadership.
I enjoy Joel's writing and think he sounds like a good guy. I'd be curious to see what he did if some of his employees left Fog Creek to start a company. The reaction would be a good measure of leadership.