I've had a case where I've used stuff like "x did q that y would undoubtedly frown at." but that's about the furthest extent of control I've taken over a character without permission, which is essentially just a presumptive statement, rather than taking control of a character.

Basically, it should go without saying that taking the reigns over the fate of another player's character or their actions is "godmodding". As you guys said, it's the act of playing god - manipulating fate.

Of course, that's somewhat allowable if you're the GM, but only to a limited degree. And that's only because the players have essentially signed a contract with the GM to put their actions under his/her scrutiny. After all, God Modding and Game Master share the same initials. Hah.