I very much doubt Harry is already a perfect Occlumens. The last word we have on that is that he may grow to be one "in time". It would an unforeshadowed and plot-convenient superpower if he was suddenly revealed as such.
Note: even a non-perfect Occlumens can apparently lie under Veritaserum, just not lie to a good enough Legilemens (even without Veritaserum).
even a non-perfect Occlumens can apparently lie under Veritaserum
Where did y'all get this? I had the vague impression that Veritaserum worked better to detect deliberate lying. Legilimency can detect other Legilimency better, because the potion doesn't do that at all. (And neither of them can detect Obliviation or a perfect Memory Charm, per Chapter 79.)
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: