Changes to Death Knight Creation

From a Blue post -

Q. Who is eligible to create a death knight?
A. Players who have at least one level 55 character on a realm may create a death knight on that realm.

Q. What if I have a level 55 character on one realm but want to create a death knight on another realm to play with friends?
A. At the launch of Wrath of the Lich King, you will only be able to create a death knight on the same realm where you have an existing level 55 or higher character. In the future, we plan to allow the creation of a death knight on any realm (provided you have at least one level 55+ character).

Guess I'll be passing on DK's for a long time.

You have more than one level 55 on AD. No worries.

True but irrelevant as I have no free slots for one.

Don't sweat it, wait until the Death Knight craze dies down and then transfer one of your characters off to make room. Or make a Death Knight on another server once they open it up.

I'm sure it will be a fun class, but I'm not gonna jump on that until my main four characters are 80.

? is there a limit to how many Death Knigths you can have
like one per realm ore just one total

One per realm (server). If you want one, be sure and pick the side that interests you.

Hmm, math ... 49 DKs available to you on 49 realms. (50 limit minus the 1 Lev.55 you need on the realm to make one.) But how many people are gonna pay for 49 transfers as you do need the 1 55 to even create a DK on the server?