Matt Cutts, Google’s head of search spam, posted a video answer this morning strongly recommending that those who place widgets on their sites, or those who distribute widgets, should place a nofollow on the links within the widget code.
Matt Cutts said, “I would recommend putting a nofollow, especially on widgets.”
The reason is because he said most people who embed the widget on their sites do not realize what else they are embedding on their website outside of the functionality of the widget itself. So, if the widget is to embed a poll on your site, it may contain a link back to the poll website without a nofollow on that link.
Google is telling the widget maker to add a nofollow on that link, so that the webmaster who is adding the widget code to their site, will not be passing PageRank back to your site without knowing.
That being said, Matt did say that links within widgets would not necessarily carry the same weight as a true editorial link.
Matt also mentioned several times within the video the infographic example of embedding infographics on your site.
Here is the full video from Matt Cutts: