Jag,
I've seen it happen with servers. It's especially prevalent with the cheaper power supplies. My friend who owns a web hosting company (burst.net) has literally thousands of servers in place, so we have a representative sample
.
We have seen PS's from multiple vendors completely blow out motherboards, or fry certain components. It's more common than we'd like to think.
TW is right. If you have machines where the PS runs in a bad way, it will cause major issues.
Mitch