The PTR for patch 5.2 has a real treat in store for people who want to powerlevel Blacksmithing: you will now be able to get to 500 skill without having to wait for those rare old-world materials to show up on the Auction House! If you are level 85 and up, all you have to do is visit your Blacksmithing trainer in your faction's shrine (the same one that sells recipes for Spirits of Harmony), and they will offer you a fast-track path straight to 500 skill.
The way it works is that you will be able to train patterns that take only Ghost Iron Bars to make grey items, and once you get up to 500 skill, there's a quest to make a Ghostly Skeleton Key. At the time this article was written, the data-mined recipes on the Wowhead.com PTR site seem to indicate that it will take a lot of ghost iron to complete. Of course, this might receive a rework before it hits live.