Matt of WordPress does not like sponsored themes. Google does not like sponsored themes either.
You know what Sponsored Themes for WordPress are. They have a link or two at the bottom or in the sidebar, linking to the sponsor’s website. The sponsors have, of course, paid the theme designer. They get a backlink from every page of the blog where the free theme is downloaded and uses, and the designer makes some money.

The problem is that Google’s PageRank - a major factor in evaluating the relevance and ranking of a website - relies heavily on links. And Google has been making it pretty clear that these links to the sponsor are skewing their PR system. It is easy, pay a theme designer, and your site gains new backlinks with every download and install of the sponsored theme. The designer is happy, and the blogger cares two hoots about Google’s PR.
But Google has been on a penalty spree, downgrading the Toolbar PR (the PR displayed on the toolbar) of several blogs and blog networks recentlyby a few notches. Have they already started doing the same to those sponsors’ sites benefiting from the sponsor links? Not yet, but this is quite likely. Google has not particularly cared about collateral damage when they do battle, and they may not care in the future either.
So what about the link back to the theme designer, on almost all free WP themes?
That is not a paid link, you can say.
It is normal on the Net to link back to the author or designer, you can say too.
But Google’s idea of what a link is, is different. For them, a link is currency, a vote. A vote that says that the linker is giving a thumbs up to the linkee. No, more than that. It is some kind of an editorial endorsement.
Now, we can argue till forever that every link on the Web is not an endorsement of any sort. It is pointless. That’s what Google thinks, and we care about what they think because it’s their search engine and they can do what they want, blah blah.
So are you making an endorsement of the designer when you use a free theme with a linkback to his site? Sure he gains PR. Was that your intention?
Was your endorsement of the designer strong enough to give a link to him from every page of your 100 or 1000 -page blog?
Even the default WordPress theme has links to the blogs of its developers. You never chose those links consciously, or intended to endorse each of them, did you?
My point here is that in the Google world, every link on the Web is to be given consciously. Not that any of us are going to particularly bother about that. But that is how it is.
The fact is, whether you do it consciously and deliberately in the case of a sponsored theme, or without caring in the case of a free theme, you are passing link juice. The blogroll links which you never removed are passing link juice. And that is not acceptable to Google.
Today, they draw a line in the sand - and say sponsored themes are bad. Ever link and little square ad on a TechCrunch or Mashable pass PR - deliberately or unknowingly. For now, they are on the safe side of that line. Maybe not tomorrow.
But it is only a line in the sand.
According to Google, every link which is not an endorsement should be NoFollowed.
Imagine a scenario where a theme designer has people downloading and installing his theme on ten thousand blogs. He gains links from every page of those blogs. This has the potential to skew Google’s PR measurements.
But so far, Google has not objected to it.
Why? I have no clue. Can they discount the effect of massive links to the designer? I have heard this is possible.
But if they can do it, why not discount the links to the sponsors’ sites too and let us all have some peace of mind? The sponsors won’t like that one bit, but why do we have to end up doing Google’s job for it?
My feeling is, there will be more such warnings from Google. Penalties, warnings, instructions, PR downgrades… as long as they do not manage to do the job of identifying and negating the effect of links which are not editorial endorsements. Some of us will be collateral damage, when they mistake a genuine link for a paid link.
And in the real world, there is nothing much we can do about it.