The Solo MMO Player just asked me the maximum level for the original game and each expansion of World of Warcraft. It was so hard to find I thought I'd post the answer here.
Vanilla WOW - top level 60 (November 2004)
Burning Crusade - top level 70 (released January 2007)
Wrath of the Lich King - top level 80 (released November 2008)
Cataclysm - top level 85 (released December 2010)
Mists of Pandaria - top level 90 (to be released September 25, 2012)
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