We have been discussing recently that for some activities in World of Warcraft, like scanning the auction house, posting hundreds of glyphs, or emptying your mailbox, you don't need to watch your screen. You can do it semi-afk. You can wander off and do something else, read a book, watch TV. Or you could alt-tab into a web browser. Not any more. I noticed yesterday that patch 3.3 had changed the way addons like Postal or Auctioneer work: They now stop working if you alt-tab out of WoW.
You can still go semi-afk and leave WoW on top of your screen. But if you want to anything else with your computer, and get another application into the foreground, your semi-afk business will grind to a halt. Makes me think that Blizzard wasn't all that happy about semi-afk gameplay.
I would have proposed a better solution: Limit the number of auctions a character can have to 100. That is large enough to not hinder any normal playing activity, but would put a stop to the "posting 2,000 glyphs" businesses. That is, if these changes were actually meant to stop the mass-production business. Maybe they were aimed at other activities, like botting? I don't know. But not being able to alt-tab out while scanning the AH is a bit annoying.