A Mac user reverse engineers the iMac G5 fans. He identifies yet another flaw: lateral play in the bearings.
Bottom line, for many Mac users a major appeal of the G5 iMac is quiet operation. It doesn't deliver. In fact, it often generates more irritating noise than a typical desktop machine. (During the winter my homebuilt XP, with several thermally controlled fans, is almost silent.)
I'm already holding off on my iMac purchases because of the problems with iPhoto 5. If Apple doesn't fix the iMac I'll be looking at either a Mac Mini or a refurbished PowerMac.