And it's not the sort of dateless you can cure with a trip to a single's night. After reading this preview of AITD 5 at YouGamers, I noticed they had "November 2007" as a release date. Thinking I must have missed the Oz press release announcing this bit of gold, I contacted Atari for the full story.
Turns out the story wasn't so full. Atari got back to me with this:
We have only been given the date of 2007 at this stage.
Still, there's only three months left in the year, so if you guess now, you have a 1-in-3 chance of being right!