Under that provocative title, Justin P Lambert actually does a great favor to Curators by outlining a key point between plagiarism, social sharing and curation.
While blog plagiarism has been as old as blog platforms - Justin shares his own story - he defines the clear line that exists between:
1. blog users who copy/paste entire articles
2. social media users who share randomly without having their "audience’s needs or desires in mind"
3. curators who - he says - "put their audience first"
Curation done right "involves figuring out what your audience wants and needs to know about and then sifting through the overwhelming amount of information out there to hand-pick specific items that you know they will benefit from." This is a pretty good definition of Curation in my opinion and one of its direct consequences is that Curation works better in a topic-centric model.
Defining a topic and making your editorial line clear is a great first step to develop an audience with their interests in mind.