Of course that you will also need the Cataclysm zones but you will get them in 8 days so...
For some reason all my characters received nearly all the zones achievement as explored and only some zones left like Orgrimmar Azuermyst and Bloodmyst Islands and others for horde. So you can use the Whack from here http://www.mmowned.com/forums/world-...ulti-hack.html and tick Speed Hack,Fly Hack,Remove objects and Remove Terrain collision and start explorer the zones left. As soon as Cataclysm comes you explorer the remaining zones and ding Explorer title!
(all those achievements date from 11/24/2010) Please post if you have that "bug" too or is it just me?