I like how a Blue posted in this thread but didn't actually answer the OP's question.
I'm sorry, Tyrathius, you're right. Unfortunately, I cannot answer this question directly, as it falls outside the scope of my assistance. I can, however, direct you and the OP to this post from Ghostcrawler:
http://us.battle.net/wow/en/blog/5367158It reads:
We hope that rewards granted from achievements (pets, mounts, titles, and tabards) will be shared at the account level.
I'm not going to promise this yet, because a lot of magic has to happen for that to work, but it's our intent. We have discussed having a character level requirement for some rewards, so that your level-2 gnome couldn’t walk around with the “Defender of a Shattered World” title just because your level-90 shaman earned it. If the gnome made it to level 80, though, you could proudly show off your title. You also won’t be able to use a faction-specific pet, mount, or title on the wrong faction. The achievement wouldn’t go away -- you just wouldn’t be able to show it off on that character. There are probably additional exceptions and details we’ll find as we dig deeper into the system.
This is the kind of system that will evolve over time, and we don’t think this has to be the way achievements work forever. As beta players start experimenting with it and offering feedback, I am certain that we will end up making even more changes.