Note that the timeline will be something like this:
 - Sometime on Jan 1 (at an arbitrary time, not midnight), the wordfilters will be put into place, the announcement threads will be locked, and mixer-run accounts will be put into PM-only-mode. If any threads/accounts are missed after all of the other ones are affected, please report them. If new wordfilters should be added, please post in a topic in Meta about it.
 - Sig-campaign (etc.) threads which appear not to be soliciting new promotion might not need to be locked at all, and wrap-up-related posts can still happen there. We don't plan on going through all of the sig-campaign threads and locking them all. But if they're continuing to generate promotion, they will be locked.
 - Mixer sigs will be affected by the wordfilter on Jan 1. After a few days (ie. not immediately on Jan 1), signatures containing any of the wordfiltered URLs will be blanked. I haven't decided yet whether I'll remove old mixer avatars: if I do, it won't be for at least a few weeks after Jan 1. (New mixer avatars definitely aren't allowed.)