if you already have an existing WoW account,but you stopped playing or whatever, you can now upgrade it for a 10 day TBC trial. i dont know if you can level your existing chars yet im downloading it now. i stopped playin cause i was bored of it but if TBC is a big change i might just start again
Get the trial here
Get the trial here
I might have to try this - I quit because I was a little too busy with some other things, but I do miss it from time to time 

) does it?