Hopefully not a repost, I thought this was some good info I'll be happily displaying my Vanilla wow pvp titles well into Cata.
The original titles are not going to be taken away from players who already have them. The Feats of Strength associated with the old titles will be changed slightly to more clearly distinguish them from the Achievements associated with the returning titles.
Here's a brief rundown of how the rated Battleground titles will function in Cataclysm, and how the original titles can be earned by players who did not have a chance to participate in the original ranking system:
As of now, the first ranks -- Private for Alliance and Scout for Horde -- are earned when a player reaches a Battleground rating of 1100. The ranks increase every 100 rating points, up to Grand Marshal/High Warlord at 2400 rating. Titles earned through the new system are yours to keep and will not be wiped with each season.
In addition, all-new titles and Achievements will be added for top performers. Hero of the Alliance and Hero of the Horde will be awarded to players who finish a season in the top .5% of the rated Battleground ladder. These titles will be wiped at the end of each new season, however, a new Achievement will be awarded to players who earn this title each season.
Let’s see how many seasons in a row you can stay in the top .5%! 
