In answer to your thread title - yes from my experience.
I've gone through two iMacs in the last 3 years (Apple replaced one). Faults have included blown HDD (ok, not really something you can predict), blown USB bus, logic board failure, Major screenburn issue, broken webcam, broken speaker, broken fan x2.
I wouldn't recommend the iMac to anyone. Whilst I still use my good ol' 07 white Intel iMac, I'm currently looking at a new Mac Pro as I cant see the point in getting another box of broken parts....which I cant replace or upgrade myself!