In August 2007 a hacker found a way to expose the PHP source code on facebook.com. He retrieved two files and then emailed them to me, and I wrote about the issue:
It became a big deal:
The two files are index.php (the homepage) and search.php (the search page)
I don't know what ended up happening to the guy who stole the code.
I found these files today while searching for another Facebook related file. Worth preserving as part of Internet history.