Google has repeatedly told the SEO community that it would not push out major updates during the holiday season, which would make this development very surprising to say the least if it turns out to be true. While Google has not yet actually confirmed that any changes were made, there has been a significant increase in SEO forum threads which would indicate some activity (whatever it is) has indeed taken place.
One thread commenter in particular revealed that new search results pages (SERPs) were showing for a few hours and then reverting back to older versions, only to return to the new SERPs again. SEOs don't seem to know what to make of the shuffling, but some are speculating that the fluctuations are a result of some general testing on the part of Google - but only time will tell.
An interesting thread at Black Hat World speculated that the changes (which for the most part improved rankings for those sites suffering from the October Penguin update) has something to do with click-through rate. A rollback of Penguin, however slight, is sure to catch the attention of SEOs who have been feverishly optimizing their sites to regain their rankings. The thread commenter posted that the movements seen were directly proportional to the CTR from the SERPs.