Reno - 7:51 pm on Dec 30, 2010 (gmt 0)
You more than most seem to be in a position to verify the "throttle effect", with a dedicated server and a decade of data behind you. But here's my question: Is it only Google that is turning on & off? OR, are you seeing it from multiple sources (G, Bing, Yahoo, etc)? If it's only G, then it appears from your posting that your biz is highly dependant on Google traffic, to the point where they can shut you down if they shut you out. If however you see the decline across the boards, then the water gets very muddy and I wonder, how can that be?
The traffic spigot turns on and off at apparently random times.