It looks like Google have confirmed the update to the Panda filter. It was announced back at the SMX Advanced conference the other week by Matt Cutts in a question and answer session with Danny Sullivan. Sources say the update was around June 16th.
There has been a mix of reports with webmasters who had previously been caught by the Panda update along with others now suffering.
The update was apparently going to address the issue of scraper sites (sites that republish other authors content) who usually make money from Google AdSense in the process.
Has your site been affected?