I had this conversation with a friend, who, having done no actual reserach on the subject herself, tried to convince me that cloth was worse for the environment than sposies. I agree with Annette: being eco isn't all about what you do, its more about the control you have of it. As well as trying to source locally made nappies at least some of the time, we also have many WAHMs who benefit, as opposed to multinational, unethical companies like pampers.
I usually wash nappies (and bedsheets and tea-towels) at 60 with an extra rinse if theres a lot in the machine, and everything else at 30. A small load of nappies with few poopy ones I'll do at 40. I'm happy enough to think that they balance each other out. I wouldn't do a 30min quick wash on nappies though, unless it was literally half a dozen, non-poopy nappies, as i dont think they'd be very well washed.