Gimmebar pulls a Readability.
When you share content from Gimmebar, it shares a shortlink to the content on Gimmebar, not the source URL.
Sure seems like content/value/traffic theft to me.
To go a step further, I think you're freeing the person sharing the content prematurely. If I see something funny on cracked.com, and decide to grab that content, upload it to imagur, then share the imagur link… Imagur getting the traffic instead of cracked is on me, not imagur.
i'm not sure how to do it, exactly, but i know it's possible to do this in a way that isn't so... swipey.
VERSUS
b) quoting all or almost all of the interesting bits from the article, and providing a link to the original.
In the latter case, there is no reason or incentive for the user to visit the source. In the past couple of years I've begun to think this is the wrong way to go about things.
There are enough tools and applications out there that let you share links and pictures of stuff you like, but not many that are completely focused on ensuring that those things you like stick around in an easily searchable and backup-able way.