What's the license for OS X generic icons? Can anyone link me to a document or otherwise provide information about what the license is for the generic icons included in OS X (Lion)? I tried searching at developer.apple.com but nothing relevant came up.

To be specific, I'm wondering about GenericFolderIcon.icns. If I copy it and customize the look, would distribution be restricted somehow?
IANAL but I would guess that all the graphical assets in OS X are copyright Apple just like everything else in the OS. 

Any assets that you are entitled to use are listed on the developer sites for which typically a licence must be signed.