My point with the virtual worlds was to put the AI into a simulation sufficiently unlike our world that it wouldn't be a threat and sufficiently like our world that we would be able to recognise what it does as intelligence. Hence the Gas giant example.
I'm not sure I follow. Gas giants run on the same physics as you and me. Do you mean a world with actual different simulated physics?
A friend of mine is about to launch himself heavily into the realm of AI programming. The details of his approach aren't important; probabilities dictate that he is unlikely to score a major success. He's asked me for advice, however, on how to design a safe(r) AI. I've been pointing him in the right directions and sending him links to useful posts on this blog and the SIAI.
Do people here have any recommendations they'd like me to pass on? Hopefully, these may form the basis of a condensed 'warning pack' for other AI makers.
Addendum: Advice along the lines of "don't do it" is vital and good, but unlikely to be followed. Coding will nearly certainly happen; is there any way of making it less genocidally risky?