Panda 2.3 Google Officially Confirms Update Live
Search Engine Land reports that Google has confirmed Panda 2.3 is live.
Panda update schedules: [a.k.a. the new "Google Dance"]
Panda Update 1.0: Feb. 24, 2011
Panda Update 2.0: April 11, 2011
Panda Update 2.1: May 10, 2011
Panda Update 2.2: June 16, 2011
Panda Update 2.3: July 23, 2011
A pattern is developing. Every month, Google manually runs the Panda algorithm. To more fully understand this read: http://searchengineland.com/why-google-panda-is-more-a-ranking-factor-than-algorithm-update-82564
In summary, Panda is a new ranking factor to filter low quality pages and not an algorithm update like "MayDay" or "Florida". The calcualtions aren't done on a daily basis. Instead it's a manual process meaning someone decides to "kickoff" the program to update the Panda values.
The short end of the story is that even if you make changes to your site to correct quality issues, the site can not recover until the next Panda update.