I guess my question is.. where is the child in all this? How old?? What a bombshell right before the holidays.

That is such a big difference between spring 2006 and now-- like 1/2 a year.
Im not sure how to cushion the blow- except that I would say to tell her sooner than later. My other advice is to NOT say to her anything in the range of "Well we told you all along that we would be moving..." That wont cushion anything...but IMO will just make it worse. Maybe offer a few extra visits this last month?!?!?
I would also probably not point out that you dont like her job or what not.... at least she has a job... and being what it is..doesnt mean she is doing anything wrong.
I would set up a schedule as to when you will send her photos during the year... and if you will be available for phone calls. You said you were open to visits... but not willing to help her at all.
Alaska to Tennessee is so far.

Would you not even consider helping? Even splitting or something? Not because you owe her anything-- if it was made clear beforehand-- but because it would benefit your child to do what you can to keep that relationship in tact for him or her.
I guess over all.. my advice is that she is going to feel how she will feel -- probably crushed... and I would just let her feel that way and not try to cushion it with letting her know that you already told her before that this would happen. Then be open for a dicussion on where to go from here.... even if it means getting to gether a few more times before you leave. Im not sure that she will be in a state of mindto talk about it right then and there at the same time you tell her.
I hope everything goes well.