So my iMac is completely dead now.
I rang the local AppleCentre and asked if they had power supplies in stock. I had dreams of them being able to replace it on the spot (assuming that is the problem) so I could be up and running by this afternoon.
"We're not allowed to carry spare parts" was the response. I'm trying to keep an open mind but I'm not sure why Apple would not allow spare parts to be kept on site at an AppleCentre. Especially given how far away Perth is and how long it takes for things to get shipped here.
The estimate for the replacement power supply to come in (again assuming that's the problem—I haven't actually brought the machine in to them yet) is 1-2 weeks.
1-2 weeks without my main non-work computer!
I (stupidly in hindsight) didn't get AppleCare on the iMac (although I have it on other Apple hardware that's never had a problem). The guy on the phone claimed AppleCare owners would get priority but given it's a shipping issue I doubt it makes much difference to the 1-2 weeks.
While I do do regular backups, there's a lot of cool stuff I've been working on in the last week that isn't in the last backup.
So I'd really like access to the stuff on the hard drive. I wonder if I take my iMac apart, whether the drive will just plug straight in to my PowerMac (temporarily replacing the second drive in that).
UPDATE: When I got to the AppleCentre I asked if they could open up the iMac right away and give me the hard drive. Fortunately they were happy to do this for me. I should be able to hook it up to my PowerMac (the one usually used for music and film) and get my stuff off. Now I don't really mind the 1-2 weeks as much :-)