WandereringPony wrote:We also now know why they only sent Dash and Pinkie in.

You....defiled....a...LIBRARRRRRRRRRRRRRRY!
And then Griffonstone was a charred crater.

It's OK, little books...I saved you from the nasty ol' griffons. No race that treats their books like that deserved friends...

OR LIFE.
Awesome, and as a librarian myself I appreciated the nod, heh.
Actually, it is interesting that Twilight interprets the Map as essentially banning her, considering it doesn't say she can't go and nothing is stopping her from going at a later time. The point ulitimately, was that Dash and Gilda needed to restore their friendship, and Pinkie was key to that, given the role she played in their falling out. Having Twilight might actually have thrown things off, since she would have been expected to take the lead.
I guess the big question now is, what kind of magic controls the map? What are its motivations and reasons for doing what it does? It sent all six of them earlier, but this time only sent two. Obviously it's because of Rainbow and Pinkie's history with Gilda, but how does it know about that history? Even if it's never explained anywhere in the show's canon, it's a pretty cool piece of magical McGuffinry that fits pretty darn well into the show's style.
Given that it was born out of a seed chest from the Tree of Harmony, I think we can see it as a vessel for the Tree, or capital H Harmony as a force that runs the tree. It's...well honestly it's pretty darn close to establishing God or at least a god like being or force tied to frienship and harmony as a benevolent guide in the Pony universe.