I've just come across http://en.wikipedia.org/wiki/Wikipedia_talk:Community_sanction
I think this is a pretty awful idea. This is an extrapolation of the concept of a community ban that has no basis in logic. The concept behind a "community ban" is not "rough consensus", as shown by an 80% vote or whatever exists nowadays, but unanimity among admins -- not one admin out of >1000 being prepared to unblock you. People seem to have got hold of the idea that a "rough consensus" is good enough here. It isn't. An ArbCom case is needed when there isn't unanimity among the community.
So much for consensus leading to "community bans". This is made ten times worse, however, with the introduction of "community sanctions" as part of official policy. This kind of thing may happen -- an admin might say to a user "keep away from Scientology articles, or I'll take you to ArbCom", and this (especially with the problem user's assent) would have the same effect. However, as a formalised process it is awful. It lends itself to people behaving without sufficient oversight or rigidity of purpose and it will be abused and open our dispute resolution process to even more criticism (some of which really is deserved).
This is not to say that the concept is totally flawed -- I have outlined above how the same effects can be had on a less formal level without this policy, declared as such without sufficient reasoning or indeed any justification from a public discussion (correct me if I'm wrong...).