Nick Wilson at ThreadWatch uncovered that Google Pilot New Webmaster Communications Initiative at a Search Engine Forums thread named Google offers advice to sites on penalty. Basically, Google sent the following email to a Webmaster.
Dear site owner or webmaster of [url removed],
While we were indexing your webpages, we detected that some of your pages were using techniques that were outside our quality guidelines, which can be found here: [link] In order to preserve the quality of our search engine, we have temporarily removed some webpages from our search results. Currently pages from [url removed] are scheduled to be removed for at least 30 days.
We would prefer to have your pages in Google's index. If you wish to be reincluded, please correct or remove all pages that are outside our quality guidelines. When you are ready, please submit a reinclusion request at [link]
You can select "I'm a webmaster inquiring about my website" and then "Why my site disappeared from the search results or dropped in ranking," click Continue, and then make sure to type "Reinclusion Request" in the Subject: line of the resulting form.
Sincerely, Google Search Quality Team
At first, I thought it was a hoax, but Matt Cutts confirmed its the real deal.
This is a great step forward for the maturity of the SEM industry. Matt Cutts also said to check his blog, because he promised to blog on the topic soon. But you must check out the detailed discussion at ThreadWatch & more forum discussion at Search Engine Watch Forums.