All kidding aside, shared is pretty broken currently. If you want to know how it was *supposed* to work, you can read TDPL, though I'm not sure that's still valid.
Ah, was it Andrei, who tried to sell the idea that shared is a silver bullet for concurrency problems? That can explain why we have two different views on shared. Looks like a repetition of the story with autodecoding (with similar rationale).
