It's interesting watching the developments unfold.
The big question is.... how can other multi-user sites control what it is that their users share?
The only way that I can think of is to attempt to educate users in etiquette, e.g. how many writers sign up to services such as Pinterest solely to share their own content?
That is, in itself, a breach of their terms of service - it just so happens that they turn a blind eye to it as long as you appear to otherwise be an upstanding and active member of their community (commenting, repinning, sharing stuff which is clearly not your own).
It's certainly something that Wizzley users need to take into consideration, do you appear to be using pinterest naturally? Or are you selfishly self-promoting? Are you doing what's best by the site as a whole?
Interesting thoughts, and one which the likes of Squidoo and Wizzley are going to need to pay attention to.
It still begs the question though, how - ultimately - are sites supposed to control what is shared and by who? They can't?
At this stage their remains the possibility that Hubpages have been banned for technical reasons, but it's interesting watching developments: http://hubpages.com/forum/topic/104620