This is actually kind of sweet, especially for a class that spends the larger portion of its time channeling dark magic and cursing everything in its path. When patch 4.0.1 hit, warlocks suddenly found themselves toting new and unexpected minions around. No, new pet skins didn't go live, and Blizzard didn't program any new demons into the game, but many of warlocks' trusted minions are sporting different names.
For example, my own baby warlock has had an imp named Pagfip who's accompanied him since his earliest days in the Tirisfal countryside, but now I've got ... Garloz? That can't be right. Most warlocks have had at least one demon's name changed. Many have lost demons they've had since classic WoW and -- to put it mildly -- they're not happy about it. Even non-warlocks have chimed in: "Zilnip, our GM's imp, is an important member of our family and we'd like him back, please."
If you're not familiar with minion names, the usual deal is they're randomly generated upon creation (whether of the minion or the warlock toon itself, I'm not sure) and remain the same thereafter; lorewise, it's assumed that you're summoning and resummoning the exact same demon from the Twisting Nether. If you really wanted to play with this, you could run with the story that your real felguard's on vacation or whatever, but this seems to be a bug that most warlocks would just as soon have fixed as quickly as possible. That's assuming it's fixable at all, and I'm a little worried that it's not; the only other recourse would be petitioning a GM to have the names changed individually. Notes Cornpuff of Uther, "It's like someone came into my house in the middle of the night and swapped all of my children with evil clones."
Thanks to Scott and Zhiva for writing in!
Update: Bornakk and Bashiok hit the forums to provide an update on this issue. Warlocks, you'll be getting your original pets back during the next maintenance period!
This is it! Patch 4.0.1 begins the slide into December's upcoming expansion. It's a whole new game from here on out. Get oriented with our roundup of everything there is to know about patch 4.0.1 and how it changes the game until the launch of World of Warcraft: Cataclysm.