Similar to what has been said last time, the lastest Panda update will affect 1% of query volume.
Here is more to that news:
Google has now confirmed there was a refresh late Friday affected less than 1% of queries. Google said, “Panda data refresh started rolling out on Friday. Less than 1% of queries noticeably affected in the U.S. & 1% worldwide.” We saw reports of this over the weekend and reported on those rumors. Google has confirmed there was an update.
Over the weekend there was a large spike in webmaster and SEO chatter at WebmasterWorld around Google’s shift in the search results.
Update: Google has now confirmed there was a refresh late Friday affected less than 1% of queries. Here is their tweet from today:
A Googler @googleFYI Panda data refresh started rolling out on Friday. Less than 1% of queries noticeably affected in the U.S. & 1% worldwide11 Jun 12
Source: SearchEngineRoundTable