First, the bad news. My iMac G5 died a few days ago. I took it to the Genius Bar at the nearest Apple Store today. It didn't take long for the guy to come back with the even worse news. The logic board and the power supply had both gone bad.
More bad news. I didn't purchase the extended Apple Care Plan when I bought the computer in 2005, so the warranty expired over a year ago.
But then, there's good news.
It turns out that the logic board/power supply problem was a known issue with my model, so even though I'm not under Warranty, Apple is still going to replace the parts at no charge. Otherwise, it would have cost me about $800.