They're sure doing their best to keep us all waiting with great anticipation (and further subscription money) through the transition!
I suspect it's still a long way off -- figuring out the map and the talents is a very minor part of putting out a whole new expansion to such a complex world!
I heard talk that the release date will be November 30, 2006. I think blizzard has been working on the expansion for the better part of a year. They aren't creating any new technology like they did with WoW, which can cause great many delays. They are just taking new lands, new instances and putting them on existing technology.
There is some new stuff in development, but thats all minor compared to writing the original coding of the game.
Well its just a matter on how many more bugs they keep finding in the expantion. A few months ago, I was seeing on EBGames site and Amazon that the expantion was going to be coming out Oct 15, now they say Nov 30, so who knows if they push it back again for the holiday season