EDIT: New discussion thread here.
This is a new thread to discuss Eliezer Yudkowsky's Harry Potter and the Methods of Rationality and anything related to it. With two chapters recently the previous thread has very quickly reached 500 comments. The latest chapter as of 17th March 2012 is Ch. 79.
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. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
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, ten.
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:
You do not need to rot13 anything about HP:MoR or the original Harry Potter series unless you are posting insider information from Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).
If there is evidence for X in MOR and/or canon then it's fine to post about X without rot13, even if you also have heard privately from Eliezer that X is true. But you should not post that "Eliezer said X is true" unless you use rot13.
Actually, if you can loop yourself more than six times at any small stretch of wall-time then you can get more than 30 subjective hours in one 24 wall-time day.
But it's implied you can't actually do that, which is why I think no more than 6 copies at any given time. Plus, if it were possible you could basically use any one day as a stopping point groundhog-day style in which you can (for example) brute-force read the entire Hogwarts library.
At any rate, the general limiting principle is that information cannot travel more than 6 hours backwards, Which I think means that when you draw a graph of a person using time-turners where you represent her using an arrow (going right for positive time, and left in 1h jumps for time-turner use), Then you can't have more than 6 hours of left-arrow in any given 24h wall-time section.
That would get rather crowded.