In the last few hours Matt Cutts has announced that Google are rolling out Panda 4.0 to their algorithm.
You may know that for some time now Google Panda updates have been incorporated into their ranking algorithm on a more live or continuous basis with a rolling monthly update to Panda. So this update is a major update to the settings and parameters of Google Panda rather than simply a refresh of Panda processing of websites.
Google Panda attempts to identify sites that have low quality content, duplicate or thin content and demote them in the search rankings. Many respectable and innocent sites were caught in the cross fire and arguably ‘unfairly’ demoted as a result of Panda. Google has recently been talking about a softer and milder version of Google Panda, no doubt this is in an attempt to soften the impact on genuine websites that do not deserve to be penalised. I expect it is this element which has been incorporated in this major Google Panda 4.0 update. Hopefully, we will see more success stories than casualties.