Now (in November 2012), we have new information. This dragon was Midgardsormr, who was not a primal; the empire had met real primals before this on other continents; and SE sticks to their story about a primal stopping the advance. This means that either they're changing it up, or that we were left to draw false conclusions in the past. I can't stress this enough: in 2010, the dragon was nameless and could have been anything. In 2012 we know he's not a primal - but did Square Enix know that back then? We don't know.
The Lalafell NPC Yayatoki use to tell you about Midgarsormr being "summoned" by the Dravnians to do battle with the Garleans, talking about the Battle of Silvertear Skies. Sadly I don't have a screenshot of the conversation just my memory, now he only says:
"The red moon falls towards us? Hah. I place no faith in such rumors. If you would peddle doom, I suggest you speak to someone with a little less sense."
Which we all know Dalamud is and even npcs know lol. SE cover up maybe?

I'm working on the Ul'dah quests now and I'm uncovering a lot of juicy bits. Hopefully have it sometime tonight or tomorrow. So far now shadowless people.