False Alarm - December 2006
There were stirrings about an update in December, along with some reports of major ranking changes in November, but Google reported no major changes.
Google Update Debunked By Matt Cutts (SERoundtable)
Supplemental Update - November 2006
Throughout 2006, Google seemed to make changes to the supplemental index and how filtered pages were treated. They claimed in late 2006 that supplemental was not a penalty (even if it sometimes felt that way).
Confusion Over Google's Supplemental Index (SERoundtable)
