Dakka Dakka has posted what they are calling the Full codex leaks and changes for the Chaos Daemon codex that is released tomorrow. Personally I have doubts on its accuracy, and not just because it comes out of Dakka, but because it would be rather reckless to post up that much of a Games Workshop, or any companies product (52 pages). Either way I will let you decide.
The link is listed in the Op of the thread, here. Note that this is a link to the thread, and not a link to their document.
Give it some salt