The manual action viewer delivers on a popular feature request. We hope it reassures the vast majority of webmasters who have nothing to worry about. For the small number of people who have real webspam issues to address, we hope this new information helps speed up the troubleshooting. If you have questions, come find us in the Webmaster Help Forum or stop by our Office Hours.
(Google WebSpam Office Hours?)
Official Google Webmaster Central Blog: View manual webspam actions in Webmaster Tools: