People saying "it can't be spoiled because of an NDA". The NDA only lasts until the official XBox360 release, but many (if not most) players will still have to wait an extra month where spoilers will freely be thrown around without NDAs.
Yes, there is no restriction on folks who get the DLC on public release for the 360 talking about it.
However, at least here, we do enforce the rules about posting spoilers in the General Section. And, if it follows most other games, there will an entire section of the boards for the DLCs, so it will be easy to avoid those whole sections if you don't want to read about it. Can't help you with other websites.