Basically it's what lots of us have been saying for a long time, Google wants to see a natural linking profile. What was fair game a few years ago, and worked very well, keyword anchor text eg "free advertising" is now likely to get you a penalty, or even worse, booted off Google.
So all those thousands of articles, guest blogs, forum posts, advertorials, all with those keyword anchor text, either bedded in the article, or in bio's or signatures are now potentially working against you.
For bios and forum signatures, it's an easy fix. Simply replace sales keywords for your site name, brand or URL, or add rel="nofollow" to your links, so these links won't pass any Pagerank, and won't have any seo benefit. But they can still have human traffic benefit, a key thing people forget when link building.
For guest posts and articles, it's a different story. Depending on the scale of it, you either need to start a clean up exercise, or simply draw a line under it, and concentrate on natural links.
It doesn't mean articles and guest blogging are dead, it just means rethinking your strategy, reigning in that anchor text, and not concentrating on one tactic. If all of your links come from articles, then the Google god will surmise that this isn't a natural link building policy.
Googles updated link policy in all it's glory is here: Googles Link Policy Was tempted to add free advertising instead of link policy, but didn't want to get into trouble...

So a brave new slave to Googles linking rules dawn is upon us...
Do you think it will cut down on the volume of low grade SEO rubbish passing through? Or lesson the number of spammy SEO emails you get? Unlikely..
So anyone got any thoughts, had or seen any recent issues?