Can't say I've seen it before and I just read a Wikipedia article linked from HN last night[1]. I'm guessing there's a threshold of visits before their software flips that switch.
My interpretation is that it's a nice way of staying "Don't argue about the content of this page here, do it on your own message board".
[1]https://news.ycombinator.com/item?id=5722458
Edit: just saw johnduhart's reply.
I've seen a similar banner for years when /. links to wiki pages. It is just a template that someone pastes on to warn editors that traffic (and thus edit velocity) will be up for a day or two.
Re:Capacitor plague
by w1ntermute on Friday May 17, 2013 @09:40PM
(#5727567)
Ah, I see. I thought it was added automatically when a lot of traffic from one referrer was detected.
Re:Capacitor plague
by johnduhart on Friday May 17, 2013 @08:53PM
(#5727477)
It's not a feature just a template someone added. It's meant for talk pages anyway so I've removed it.
> On 18 May 2013, Capacitor plague was linked from Hacker News, a high-traffic website.[0]
Does anyone know the rationale behind adding this? It doesn't seem like they're auto-locking/semilocking the article to prevent inappropriate edits when an article is linked to from a high-traffic site.
0: http://i.imgur.com/LWwRQXF.png