With my Druid's tank and heal sets close to where I want it to be, I last night got dual-spec for my Death Knight and made her into a Unholy-tank (for multi-mob agro generation). Since my primary DPS spec is a Blood single target spec, I could continue to use that on easy bosses (while in Frost presence).
My Druid has not tanked a heroic yet. I'm waiting for one of the easy heroics to be the daily to give it a try.
For my DK, it was shocking to see how little tank gear I had. I have a good weapon, and 1 tank ring - everything else is DPS. So I hit the Auction house as well as the guild bank, and got some late 70s blues to help get close to the 540 defense rating (sitting at 450 at the moment).
I also got the new set of glyps, but not sure if my minor glyphs are the right ones. Will have to play the DK a bit as a tank tog et a better feel for it.
My my Druid last night I did Vault of Archeron raid for the first time. Had a solid raid and we took down all 3 bosses. I got 1 heal upgrade, so I was happy.