1script - 10:32 pm on Dec 23, 2012 (gmt 0)
Just adding one data point to this thread since it may be safe to assume there won't be many other updates here in a while due to holidays.
Looking at my Analytics stats as well as stats I collect myself, I cannot confirm this. If I go by Analytics, my no referral KW visits actually dropped 2% although my own stats show literally only 0.1% difference between pre-16th and post-17th no-KW Google visits. I think the difference is caused by traffic from Google's non-.com domains which I didn't separate in my own stats.
- Sites affected showed a sudden large increase in "not provided" keywords in analytics
In any case, there was no "sudden large increase" in "not provided" keywords.