TheMadScientist - 5:04 am on Jun 4, 2010 (gmt 0)
It was the 17th of May and corresponds exactly with the timing backdraft7's comments note. Interestingly backdraft7 didn't note a difference in traffic, but a definite difference in sales... I saw both, but they went in opposite directions and really made me scratch my head a bit, because traffic decreased while other 'the right page is being returned for the right searches' signals increased, including time on site, sales and page views.
Yesterday and today my visits went back up, but my page views dropped from 3 to 2 and time on site went from over 2 minutes to 35 seconds. I didn't change a stinking thing that could have cause the difference... Nothing. Nada. Zip. Ziltch. The site is exactly the same as it was May 1, May 17, and June 1.
Much like backdraft7 I don't see the difference in terms during the time period, except for a slight shift and drop in long-tail searches and even the shift in terms is small...