A WebmasterWorld thread has an SEO claiming he received a response from Google to a reconsideration request that the only way his site will be reincluded in Google is if he removes all or most of the links in those WordPress themes.
He said, years ago, he partook in creating and sponsoring designs for WordPress themes. Part of that includes a footer link that says "designed by X" or something like that. You see them all over the web, not only on WordPress sites. He said, Google told him, to be reincluded, he has to get rid of those links from those themes.
But this SEO says the themes are out there and he won't be successful in getting most of them to remove it. Probably most of the blogs using it are on auto-run and never get touched by a human. So what can he do?
As Robert Charlton said, Matt Cutts did go on record about these sponsored themes in 2008.
But that being the case, now what?
A senior member named Planet13 suggested that:
Redo the templates without the footer links.
then try and contact the website owners and notify them of an "update" to the template and how important it is for security reasons to keep their templates up to day.
Either way, if you have sponsored themes out there and have yet to received the unnatural link notification, you might want to jump on this sooner than later.
Forum discussion at WebmasterWorld.