We had a little bit of controversy in the first installment, so I'm just going to state this as baldly as possible; if you hated what I wrote last time, there's a good chance you'll walk away from this one thinking I eat babies. Delicious, delicious babies. While I never mean to offend people, I reserve the right to tell them the truth, or at the very least a highly entertaining and plausible lie.
Truth, she be at times an ugly mistress. And she ain't gettin' any prettier as we move from DPS to tanking.
Tanks have significantly more responsibility, both in groups and raids, and they face the competing directives of maximizing mitigation (to keep their healers happy) and maximizing threat production (to keep their DPS happy). I've healed dozens of Death Knight tanks at this point, and while the average pugged DK tank has gotten noticeably better, there are still a few trends you'd want to be aware of as a healer. The problems in beta right now are made worse by Blizzard unintentionally overselling the ease of tanking on a Death Knight in 5-man runs. Many people seem to have interpreted the statement that they should be able to tank well with Blood, Frost, or Unholy specs as being tantamount to saying they can tank well regardless of how their talent points are spent in those trees.
Any experienced tank can tell you right now that this is not true, but people believing that it is is how you wind up with 11K-life Death Knights taking 7-8K enraged hits from Keristasza in the Nexus. If you've never tanked before but you're interested in tanking on a Death Knight -- or pragmatic enough to know you'll probably wind up tanking a certain number of 5-mans on your DPS Death Knight -- I hope this article helps you avoid what I went through in May 2007 when I started tanking and sucked at it.
I came to the beta to slowly lose my mind trying to heal insane tank damage and gulp Extra Strength Tylenol. And I'm all out of Extra Strength Tylenol.