BFL. He’s good.
It concerned replicator-based teleportation. You know, the kind that scans every molecule in your body (destructively, mind you), and commmunicates the composition and structure to some distant molecular assembler, and out pops....you? Or some monster resembling you? What happens to your consciousness, your soul, your sense of self, in the process?
I said I wouldn't do it. It wouldn't be I that popped out the other end; The real I'd be consigned to oblivion. For one thing, quantum considerations alone would make simply impossible an exact copy, and I suspected that the mind itself is based, partly but critically, on quantum effects.
If I recall, he basically agreed, and suggested I read his latest novel at the time, Cosm.
A few years later, I was discussing the concept with a friend at work and he suggested that I watch the movie The Prestige. It brought up similar questions in a slightly disturbing way.