Come the next patch, all emblems will be converted to Justice Points, which is the new currency for buying tier items. You may be thinking "hey, I can farm heroics now so that I can just buy all the level 85 tier gear as soon as Cataclysm is released", but the conversion rate is awful for existing emblems. Right now, an emblem of Frost or Triumph converts to 2.75 Justice Points. In the PTR, the Tier 10 helm costs 1100 Justice Points. So, if you save up the emblems to the next patch, you're essentially going to waste 400 emblems to purchase something that costs 95 emblems now.