jakebohall - 8:00 pm on Mar 4, 2013 (gmt 0)
In my experience, Zemanta is a great way to assist in building a natural link profile. You provide them with a feed of content from your site, and they recommend it to publishers authoring "semantically relevant" content.
You pay on an impression model for the recommendations to appear for the bloggers in a list of other recommendations. There is no incentives (that I am aware) for bloggers to use your content over others.
The anchor text of the links is typically the title tag of the page being linked to.
My only issues with this strategy are in the pricing model. Zemanta seems to be above board and in compliance with Google TOS.
With Zemanta in particular (I don't have experience with any of the others), the links are placed in a way that does make them easy to pattern match across sites, but as far as I am aware, there is no duplication of content outside of the anchor text of the link being the same if linked from multiple sites.