Intrigued by the Island Four riddle, an anonymous reader forwarded a piece of correspondance between him and Nathan, perhaps offering us a hint or two:

It does indeed have a meaning related to Halo. Someone will find it eventually ... but no one's really close yet. I get the strange feeling Hamish (Sinclair) knows, but isn't telling. He gave you guys a BIG hint on one of his story page updates (probably around the 5th or 6th, just before I left).

That is, of course, Marathon's Story he was referring to. Time to go scour the archives...