Read this post AND the comments: http://www.mattcutts.com/blog/how-to-report-paid-links/
Now I have just started reading the comments to this post, and I haven't seen a follow up comment by Matt yet... but this is VERY serious. I'm hoping after I finish going through the comments, Matt elaborates on this more.
Post your thoughts, and I (or anyone who finds new info before me) will post updates as I find them.
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