Wow. I tried turning off themes, using my own CSS and no matter what, the Zemanta backlink is there. I see how popular the plug-in is with hundreds of thousands of downloads and I must admit it does have value, however the Zemanta link embedded in each and every single post page is not a good thing - for me anyway. It's great for you since you have countless millions of backlinks and many people obviously do not question those kind of "questionable" practices because they are just happy to have a pretty plugin.
I was pretty much done with Zemanta anyway and at the very end I reconsidered after I saw yet another plugin by you guys and tried it howeverm after seeing the "cost' of it, I have installed it and restored my database because it makes me wonder what else was "embedded in my theme" by Zemanta.