mhansen - 5:11 pm on Nov 23, 2012 (gmt 0)
Much more likely is that user intent changes for the holiday season.
We have access to several tightly focused sites, all under the umbrella of a common broader informational niche market targeting US visitors. ALL of the sites started losing Google referrals around 10-11pm eastern time on Weds before Thanksgiving. Slow to dead all day yesterday, then around 11am ET this morning (Friday morning) the Google referrals came alive again.
Traffic from Other than Google engines was slow, as we expected for the holiday, but Google traffic in particular was almost gone, much lower than other engines, which never happens. Almost like they swapped to a "transactional" set of results in the parent niche market, where all queries brought up transactional results versus informational.