The last minute or so (3:55 into it) in Part 1 of this video interview with Jeff Kaplan (THE Game Director or World of Warcraft) talks about his stand on multiboxing...
http://www.beckett.com/beckettMOG/default.osi?v=3
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EDIT: Updated the link since they changed the order of the videos on the page.. Big Hey to Bearhug from my Shaman in Nagrand where he was catching flak for multiboxing.