4chan Source Code

Is there anywhere to download the source code of 4chan/other image boards? I'd like to see it just out of curiosity and to possibly set one up for myself and friends.

There was a thread on either here or /g/ a month back where an internal server error allowed a user to download the imageboard.php file, perhaps not a great use without the includes etc; but none the less useful if you were infact looking for exploits. Perhaps somebody has it; at any rate the original was posted on pastebin.