Sgt_Kickaxe - 12:21 am on May 31, 2010 (gmt 0)
Another thought while working through all the "possibilities". Perhaps google has categorized the net. If it deems a search query to be about something in the widgets category perhaps the scope of possible longtail results is now limited to sites that fit that category. That theory would support what happened to webmasterworld. I'd be interested to know if the missing long tail search term traffic to this site could be construed as having looked for "non webmaster category" content.