You can buy a key online now from Blizz:
http://www.wow-europe.com/en/burningcrusade/download/
where was this Jan 16th @ midnight?!?
Intentionally not available =)
Heh, yeah, Blizzard is evil. They wanted to laugh at all the addicts standing in line at midnight freezing thier butts off.
They could have been like Sony and made it available for preorder download ... with the catch that if you got the retail version you got a special figure/ingame item/title/trinket once it was released. Many people bought both so they could have the expansion the moment it was released as well as the retail for the prize inside, usually for the same price as the preorder download.
I'm still debating which is more evil. ]:D