I hadn't planned to write any more about Scoop.it for a while because I feel I've said enough for now, but I was involved in some interesting discussions yesterday that are worth recording.
First on the question of "do I need this"? Maybe not. If you don't feel you have a burning desire to share items with others, or if Tumblr or Posterous are working well for you, you probably don't need Scoop.it.
@psychemedia complained about having to click through layers to get to original content, which is true, but also the point of Scoop.it (interesting scoop from Robin Good). Curation inevitably involves the creation of a curation layer, which is also social on Scoop.it if you want it to be. Again, if you don't want to curate, don't use Scoop.it.
Finally, I was thinking about the parallels between Scoop.it and delicious. I also curate on delicious, but primarily I store information there for myself, whereas Scoop.it is outward facing (although it would benefit if the tagging window popped up from the bookmarklet so that tagging is not an afterthought). But I don't overtly share with others on delicious, although I am aware of the social aspect and follow what my network stores avidly (thanks to them all). (My Scoop.it network is becoming increasingly useful as I slowly build it.) Why the difference? Although the last ill-fated Yahoo revision of delicious attempted to add social sharing features, they're just not slick enough to make them automatic. In contrast, the social network integration in Scoop.it has hit the sweetspot, making the rebroadcasting aspect of curation work. That's the difference between curation and simply bookmarking.
What I still haven't figured out is how to use Scoop.it for education, beyond the informal contexts that I'm already using it for. Maybe I should go all Illich and not try.