Here is the blog where the arrangement was first explained.
Unfortunately the whole GameTap thing isn't very clear on the new site right now, but as Legolas noted, this new version just went up at about 5:00 this morning and then the people who were up all night working on it went home to go to sleep.

Once they're had some rest, we'll get some clearer messaging up about the game's Nov. 1 availability and the 15-day exclusivity at GameTap.