When it comes down to it, most of the signals Google uses to rank the web's content are rooted in quality. Google's constantly changing algorithms are specifically geared towards creating a higher quality search experience for its users. Not everyone believes that, but it's generally the stance Google takes. When Google releases its lists of changes it has made for each month (as it did today for August and September), it calls them "search quality highlights". It's ALL about quality.
Still, only a certain subset of the changes are directly related to "page quality". Presumably, that means the quality of the web pages it is ranking in organic search results (even if less of them are making the first page these days).
The Panda update falls under the broader "Page Quality" project banner. In August's list, Google notes that it refreshed data for the Panda "high quality sites algorithm," and this is listed under project "Page Quality". This is not the only page quality change Google announced on the big list of 65 changes, however. There are three others they are:
#82862. [project “Page Quality”] This launch helped you find more high-quality content from trusted sources.
#83689. [project “Page Quality”] This launch helped you find more high-quality content from trusted sources.
#84394. [project “Page Quality”] This launch helped you find more high-quality content from trusted sources.
Really helpful. I know. That's as specific as Google is going to get on that. It's Panda and these other vague changes. There were three known Panda updates/refreshes in August/September. See the dates here, yet there were four Page Quality changes in these lists for that time period, and only one of them is specifically described as Panda by Google.
It should tell you one thing, however. The search industry press may talk about Panda a lot, and it has certainly wreaked havoc on plenty of webmasters and businesses, but Google is always making other changes directly related to the quality of your pages that don't carry the Panda banner, though from their vague descriptions, they seem to set to out to accomplish the same basic thing.
It always comes back to quality content. See our article on the EMD Update and Panda here.
Image: Awesome fat Panda eating=]] (YouTube)