heard about it? me too...
i also looked into those three files and all i can say:

dear facebook founders,

please hire someone who can actually "code" in php because what you run on your site is called crapcode.

with kisses,
the blackhat

... oh and:

dear facebook code leaker,

please pay someone to actually find a leak because a leak is much more then three files full of includes and function calls.

with kicks in the ass,
the blackhat