OS X Lion apparently changed the cookie storage format in one of the recent minor releases. If you use Safari 5.1.x under Snow Leopard, cookies are in Apple’s well-defined Plist format, which is generally stored as XML. If you use Lion, that file still exists, but the actual cookie storage has moved to binary garbage.

Not the Core Storage model they usually push on everyone, which is a perfectly sensible SQLite database, but an on-disk representation of the NSHTTPCookieStorage class, containing a mix of big-endian and little-endian data. Use Apple’s method calls to read and write it, or prepare yourself for pain.

(via jwz, who is quite naturally baffled by this giant leap into the Nineties)