MTV website has a little editorial about the Burning Crusade and Jeff Kaplan of Blizzard. Go check it...
"One of the core tenets of 'WoW' design philosophy is to not design around super-long extended-play sessions," he said. "We really focused on the winged-dungeon approach." That means they've made areas designed for players to quickly get in and out, knocking through one 45-minute wing at a time. "We felt that gave people the option of doing a bite-size chunk of content on their own time, and should they choose to take four or five bites in a night, that's kind of a personal decision."
http://www.mtv.com/games/video_games/ne ... id=1550175