The Politics of Hell
The Politics of Hell I agree is a great article. It was reprinted in the Best of Dragon Vol. 3, I don't remember which Dragon it appeared in originally.
In the article Satan was replaced but Beelzebul IIRC, also thrown out of Hell was Satan's Lieutenant who lead the Hosts of Hell, a devil named Belial, this is another Belial not to be confused with the Lord of Phlegethos, the 4th Layer of Hell.
Asmodeus later overthrew Beelzebul when he got the other Arch-Devils, who were not satisfied with his rule of Hell. The overthrow was done without fighting when Asmodeus approach Beelzebul and told him he lost the support of the other Arch-Devils. Asmodeus managed to prevent Beelzebul from attacking by convincing Beelzebul to call the most 'trustwrothy' of all the Arch-Devils: Astoroth, the Treasurer of Hell, the only Arch-Devil to ever refuse the rulership of a layer of Hell. When Astoroth enter the room he said "Hello Baalzebul, Hello Lord Asmodeus" Baalzebul knew he has already lost the conflict. Appearently the name change was highly signifigant showing that Beelzebul was no longer in charge of Hell. Asmodeus gave him the 6th and 7th layers of Hell to rule, something no other Arch-Devil had.
If you haven't guessed I love that article, though it's been years since I have read it I might have gotten a few things wrong. It is truely a great article. One of the best I have ever read.
Oh and Grazzt, I'm really looking forward the Tome of Horrors.