Sometime back Google emphasized the webmaster for a potential penalty for a follow link in the widgets,
But after Penguin 4.0 we saw a lot of the warnings were taken care of by Google itself like Discounting Bad or Spammy Links Google has been Granular and Transparent lately,
John Muller in a Webmaster Office Hour Video Hangout Confirmed this that Google is going to treat all the links inside a widget as a “No Follow” for the webmaster who didn’t do it or couldn’t do it so all the links going on from the widget is not going to send ay kind of Endorsement.
John Muller Said :
We recommend that people put nofollow on links like that [widget links].
For large (something) we notice those things too, espesially those things that are larger scale and we just nofollow them on our side.
So essentially we crawl these sites, see these links and say oh, these are all the same widget, we will just nofollow of of these links for them.
Here is the Link to the Webmaster Central Office Hour Hangout in which John Said Exactly at 54:28 Mark
Follow The Links