Quote from: Crygil

We are making some adjustments to tank survivability based on what we’re seeing in Icecrown Citadel. We feel this is particularly important in preparation for upcoming Heroic attempts. This is tricky and occasionally subjective, so we might very well make more adjustments as we get even more data.
Paladin:
# Sacred Duty now provides 2 [...]

Quote from: Zarhym

We recognize that many plate tanks are making their gear choices based on the amount of armor they’re provided, as this is currently the most preferred stat. In order to make the tier-10 plate tanking sets more desirable, we will be adjusting the stats on the gloves and chest pieces in order to [...]

A very nice guide written by Dorkbad of Kul Tiras, Europe. Original guide can be found on wow-europe Death Knight forums.

or lack thereof:

Quote from: Zarhym

It’s not very likely you’ll see a viable two-hand Frost raiding build any time soon. Each death knight tree already offers a good deal of versatility given that there are potential DPS, tanking and PvP avenues in each. They’re designed so that players can choose their path based on play style [...]

Update: Warlock, Mage and Rogue sets added!
Blizzard have officially released some high res screenshots of Tier-10 armor sets, so far the classes previewed are: Death Knight, Druid, Hunter and Warrior with the other classes to be added soon. You can check them out here: http://www.wow-europe.com/en/info/underdev/3p3/tier10sneak.html