Harry testifies: "Voldemort did it all. He made me watch with the Imperius curse -- just like when he made me help rescue Bellatrix Black."
Harry provides details of the Bellatrix rescue that only a participant would know. His accuracy can be verified by Azkaban Security Director Amelia Bones, who just happens to be present in the Wizengamot.
Harry's knowledge of the Bellatrix rescue proves the villain who Imperiused him was really Voldemort. Who else would rescue Bellatrix?
If anyone expresses doubts about Harry's super-Patronus, Harry immediately takes the excuse to annihilate a Dementor, one of which also just happens to be present in the Wizengamot.
Harry's Occlumency lets him lie through the Veritaserum about being Imperiused and witnessing poor Hermione being framed by Voldemort. He likewise lies that "Voldemort" (not Quirrell) took him to rescue Bellatrix.
Harry explains that seeing Hermione about to be condemned to Azkaban gave him the strength to finally break free of Voldemort's Imperius curse and tell everyone the truth. (Alternately, Obliviation and a Pensieve Harry wasn't supposed to find.)
Hermione is deemed innocent. Voldemort is acknowledged back in the world and is blamed. Harry can no longer be blackmailed about Azkaban because he's admitted it.
Harry-irony points for saying right in front of Lucius: "I didn't want to help Voldemort, I was under the Imperius curse".
Author-irony points for having Harry lie to blame Voldemort for two crimes that Quirrellmort is in fact guilty of.
Well you've at least managed a "confess" possibility that isn't completely insane, which is rather a feat. Of course, Dumbledore and some others know about the Occlumency thing, which means that there's a rather gaping hole in the explanation. Also, he took months to come forward, which is sketchy, and he said not five minutes earlier that he didn't know whose plot it was. Also, everyone thinks Voldemort is dead, and I didn't think an Imperius could be broken in the HP universe. Still, it's an improvement on that line of thought.
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: