I had site ranked 1# for few strong keywords in it's own niche, and after penguin update the site just disappeared from google i have sent reconsideration request and they told me this:
Dear Site Owner or Webmaster of
http://www.domain.com/,
We've received a request from a site owner to reconsider
http://www.domain.com/ for compliance with Google's Webmaster Guidelines.
We've reviewed your site and found no manual actions by the web spam team that might affect your site's ranking in Google. There's no need to file a reconsideration request for your site because any ranking issues that you may be experiencing are not related to a manual action taken by the web spam team.
Of course, there may be other issues with your site that affect your site's ranking. Google's computers determine the order of our search results using a series of formulas known as algorithms. We make hundreds of changes to our search algorithms each year and we employ more than 200 different signals when ranking pages. As our algorithms change and as the web (including your site) changes, some fluctuation in ranking can occur as we make updates to present the best results to our users.
If you've experienced a change in ranking which you suspect may be more than a simple algorithm change, there are other things that you may want to investigate as possible causes, such as a major change to your site's content, content management system or server architecture. For example, a site may not rank well if your server stops serving pages to Googlebot or if you've changed the URLs for a large portion of your site's pages. This article has a list of other potential reasons why your site may not be doing well in search.
If you're still unable to resolve your issue, please see our Webmaster Help Forum for support.
Yours sincerely,
Google Search Quality Team