I have 6 "official" aces. My first on STA #9, one on Kia #8, and the other 4 all on Oakmont's 6th hole...twice during qualifying that year, 2 more since then.
I would imagine that as many times as a lot of us play a course, especially in unlimited tournies and Open qualifiers, that there are a bunch of folks that have done it. Guys like Bollox, Jake, and others have probably gotten the hat trick on most of the par 3's.