Not sure about here. Probably not a great idea, but I saw it happen this AM as a person who just rambles on about HP switches had all their posts vanish at once.
Not a great idea at all, and there's no way in hell Theymos would implement something like that on this forum. I can see how it would make sense on the Juniper forum where people are probably looking for support--and they're corporate, but free speech is king here.
That's not to say I wouldn't support something like that, since shitposters and spammers are easily identifiable and don't usually become productive members of bitcointalk. The ignore button is fine for each individual, but a shadowban system would "protect" the entire community from having to see garbage posts and wouldn't put the burden on each member to add the spammer to their ignore list.
Given the level of freedom of expression in this forum, I think that such a thing has no chance, because it would definitely be understood as censorship.
There's a low-level baseline of censorship here anyway, if you consider that there's a rule against low-value posts and spamming. It's not as if everything goes on bitcointalk, and it's why we have the "report to moderator" button. Even in Theymos's mind freedom of expression has limits, as it should on a discussion forum like this where making posts often leads to members getting paid.