Google panda is known for filtering the poor content which is used for the Google Search Engine Optimization (SEO). The sites containing poor content are removed from top rankings. It can be known as filter which keeps on updating from time to time.
After the new update the eliminated sites can recover back to the top search list and the websites which are in the top search list have a threat to get eliminated depending on the content protocols set by the new panda update.
Google is planning for a new panda update in upcoming weeks. It is said that it would be a data refresh (new database creation would be done). Hence, it is a golden chance for the websites which have gone down in the search previously get a chance to recover back. Not all sites would be recovered, as their positions would be decided considering updates done at that time. New regulations of the update may affect newly designed sites.
The main reason behind this update is to discard sites that are developed just for visits and hits and not exact contents. This update would be more from user prospective as they would get good quality content to read and also keeping in mind the strategy of Search Engine Optimization.