The "real" #10000 is HibyPrime himself (who created this thread!) and it was on Sept. 30 at 9:03am, EDT time (GMT-4).
Here's the post, look at the number:
http://moi-alizee.us/forums/showthre...0000#post10000
To verify again: click the link and move the mouse above the "Quote" button of his post. In the status bar, you'll read the number 10000.
That's without counting all the deleted posts, so the counter was still in the 9000 on Sept. 30, but that's still the
real #10000 anyway!