In canon, the hat is considered a relic of Gryffindor specifically, which is why his sword can be drawn from it. The Wikia seems pretty clear on this, so we should expect EY to follow that. OTOH, Salazar managed to insert his own subroutine into the hat, so as I said, this doesn't really contradict cultureulterior's hypothesis about Rowena.
In canon, the hat is considered a relic of Gryffindor specifically, which is why his sword can be drawn from it. The Wikia seems pretty clear on this
Quoth the wiki:
...The Sorting Hat was sewn roughly one thousand years ago and was merely a normal hat belonging to Godric Gryffindor. When Gryffindor, along with Salazar Slytherin, Rowena Ravenclaw and Helga Hufflepuff, wondered how they would continue to sort the students when the four were dead, Gryffindor pulled his hat off of his head and, with the other founders, enchanted it with brains and some amount
(The HPMOR discussion thread after this one is here.)
This is a new thread to discuss Eliezer Yudkowsky's Harry Potter and the Methods of Rationality and anything related to it. There haven't been any chapters recently, but it looks like there are a bunch in the pipeline and the old thread is nearing 700 comments. The latest chapter as of 7th March 2012 is Ch. 77.
There is now a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author's Notes.
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: one, two, three, four, five, six, seven, eight, nine.
As a reminder, it's often useful to start your comment by indicating which chapter you are commenting on.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: