santapaws - 2:41 pm on May 5, 2008 (gmt 0)
i think this depends on the search. I have seen fixed position rotation on different serps at different positions. Have seen this for about 3 weeks. The site that gets rotated is either in that exact spot or nowhere to be replaced by another site that is either in that slot or nowhere and so on. Other results staying the same or slightly fluxing.