There is a brand new Death Knight Q&A up on the official Wrath of Lich King site.

World of Warcraft: Wrath of the Lich King will add a new option to the game’s class roster with the introduction of the first hero class, the necromantic death knight. During the Second and Third Wars, the people of Azeroth learned to fear these merciless, unholy warriors and their terrifying runeblades. Leading legions of the undead into battle during the Third War, the Lich King’s death knights proved both their strength and their cunning on several occasions, making them an invaluable part of the Scourge army.

In Wrath of the Lich King, you will be able to pick up a runeblade, don some plate armor, and wreak serious havoc using both melee abilities and offensive magic. To give you an early glimpse at the design philosophy behind the new class, we sat down with the World of Warcraft design team to talk about the role the death knight will play in the expansion’s story as well as in its gameplay, and to get their thoughts about goals and ideas for the new class.

What will be the Death Knights starting area? Nobody knows it seems.

We have some kernels of ideas that we are waiting on to pop in the microwave of development right now. ;)

No other information is available as of yet, but I will say that we want to find a way to give people an experience when working on becoming a Death Knight so that they understand the lore of it and learn how to play it both.

Here's an official Blizzard Poster post over at the WoW forums that sums up some of the things we know about the Death Knight class, and answers a few questions.

There are a lot of things still being worked out with the Death Knight class such as specific spell abilities. Unlike a traditional caster type however, a Death Knight's spell power comes from runes that are etched into their blade. Think Warcraft III when you think about the possibilities of abilities for the Death Knight. I say possibilities because things are still in process for the development of the class and there will be (of course) a lot of testing for balance done. Given that this is our first Hero class we're unveiling, you can be sure we're going for the coolest of the cool for this class.

Here's some details on the new Death Knight class that is coming with the expansion...

The Death Knight will be a plate wearing DPS/Tank hybrid. Once you have hit level 80 with your main character, you will have the option of undertaking an epic quest to ‘unlock’ your Death Knight character. Supposedly any race can be a Death Knight and you will start out as a higher level character, probably in your 60 - 70. The Death Knight is considered to be an alternate, advanced class to be used in end game play only.