A topic most SEOs already know, but it is nice to have confirmation from Google. A Google Groups thread has Googlers responding to a Webmaster who's site dropped from a PageRank 4 to a PageRank of 0. It appears this site saw a drop in PageRank, but not a drop in rankings, because it has done Paid Review posts without a disclaimer, said Google.
Anyhow, I would just move all the paid posts to a category "paid reviews", add a disclaimer to each saying, this is a paid review, then nofollow the link to the company to not share any pagerank.
Then when one member suggested complying with Google's recommendation and then submitting a reinclusion request, Google said not to bother.
Excuse me, but what reason do you see to file for reconsideration? I already see nofollows in there and the site appears to be doing fine. Not seeing PR does not mean a penalty.
So all the PageRank reductions, most without any traffic drops means those sites were not penalized. If you read the thread carefully, you will notice how the Googler keeps sharing how well the site ranks and that PageRank, in this case, is not an important factor.
Forum discussion at Google Groups.
Clarification: Admin Aaron is not a Google admin. Google did recommend sending a reinclusion request in this case. Google did not say it was a penalty, but they did not say it was a penalty. In either case, the site ranks incredibly well with a PR0. Sorry for the mis-information, I am still under the weather.