I hear this question now more than ever before. The reason why? Since the beginning of the year, hundreds of thousands of webmasters (heck, maybe even millions) have received a warning similar to this:
Google Webmaster Tools notice of detected unnatural links to http://example.com/
Dear site owner or webmaster of http://example.com/,
We’ve detected that some of your site’s pages may be using techniques that are outside Google’s Webmaster Guidelines.
Specifically, look for possibly artificial or unnatural links pointing to your site that could be intended to manipulate PageRank. Examples of unnatural linking could include buying links to pass PageRank or participating in link schemes.
We encourage you to make changes to your site so that it meets our quality guidelines. Once you’ve made these changes, please submit your site for reconsideration in Google’s search results.
If you find unnatural links to your site that you are unable to control or remove, please provide the details in your reconsideration request.
If you have any questions about how to resolve this issue, please see our Webmaster Help Forum for support.
Google Search Quality Team
This warning by itself is not the problem. The problem is that the warning is typically accompanied by either a drastic drop in SERPs, or your domain being completely deindexed by Google.
The latest word on the e-street is that simply submitting a “reconsideration request” via Google Webmaster Tools isn’t going to get your site’s ranking or indexation penalty removed. The only viable method seems to be doing your best to have all spammy backlinks removed, and then communicate it to Google.
Check out the top response in this SEOmoz thread to read how…
Another option, if you feel your site was unfairly targeted by the latest Penguin update, is to fill out this form. It’s unclear exactly what effect it will have though, it’s possible that Google is simply collecting data.