There is an article on paid links written by Matt Cutts and and Maile Ohye that was posted up on December 1. Nothing new, but it does contain a summary of all that has been previously written by Google and Cutts on this subject: http://googlewebmastercentral.blogspot.com/2007/12/information-about-buying-and-selling.html
I think the article posted on Matt Cutt's personal blog goes more in depth into the matter (rather than provide a timeline and Q&A). Google seems to target places where it expects paid links to be placed at (e.g. blogrolls, review sites)
There is a big and very professional history site out there, although I'm not going to post up its url. At the bottom of their index page they are blatantly selling links for pr purposes. If you saw the page, you'd spot it right away. I first noticed it a couple of months ago, but decided to just email them about it in the light of the above article. I just don't think that they are aware that they are doing anything wrong. The site has been around for years and they have probably always sold space there.
Thats true, they are penalizing sites which have signed up with 'get paid to blog' network sites like ReviewMe, PayPerPost etc. This has been a major blow for webmasters and blog owners especially.