My guess radar predicts January 2009.
In a press release from Vivendi they state that a 2nd half of 2008 release for the 2nd expansion to World of Warcraft is anticipated. Let's define that. Anticipated = Expected to arrive. So by that definition, Blizzard is expected to deliver the goods within the next 6 months or so. I wouldn't be surprised to see a Blizzard press release soon that goes something like: The 2nd expansion to World of Warcraft is anticipated to be released. (dramatic pause) When it's released.
Very good operating achievements were offset by non recurring or calendar impacts: the first quarter of 2007 included notably the successful launch of the first expansion set World of Warcraft: The Burning Crusade (the second expansion set is anticipated to be released in the second half of 2008) and the favorable settlement of a tax litigation.
Full press release at Vivendi.