Tigole hit the forums and talked about Player Titles in Wrath of the Lich King:

We want titles to be meaningful in WoW and not commonplace. Our goal is to release more titles sparingly, so that the titles carry weight with other players. We do have a lot of plans for some new systems incoporating titles in Wrath of the Lich King. More information will be coming out on that soon.

Also, we feel like we have to be careful about rewarding people for behavior that might not be the best game experience. As much as everyone loves killing Murlocs, I feel like I have a moral and social responsibility not to encourage you to grind out 10,000 Murloc kills.

You'll always be the Scourge of the Murlocs in my book, Lexorn. No need to grind that much ;)