Well this is interesting and a turn up for the books over on mymmosite's forums. For every player that purchases Warlords of Draenor you'll have the opportunity to level any character, for free, to 90. That still sounds absolutely stupid to me and I've no idea why Blizzard are doing it. But, if that wasn't food for thought it transpires that Blizzard are actually peddling a level boost, all the way to 90, for $60.
There's a discussion to be had by the community and the wider industry about how expensive a micro transaction should be. Personally, I have absolutely no problem with it. If someone has money, little time, but a desire to play, why shouldn't they be able to participate in the game alongside everyone else?
Many will disagree with me here and considering it costs more than the expansion itself, it's not a decision many players will take lightly. I think the primary purpose has got to be to remove levelling services from those pesky Chinese farmers. To read all about it, head on over.