landmark - 9:24 am on Feb 2, 2007 (gmt 0)

I really believe that the ups and downs we are seeing during the past month or so are not related to any changes that webmasters may have made to avoid any penalty, but are simply due to Google changing its mind about what penalties to apply.

I have not made any changes to my sites (apart from routine updates) yet pages bounce up and down seemingly at random.

Either the guys at Google are in panic mode making constant tweaks to their algorithm to try to get it right, or they have introduced some fundamental instability to the system that is causing small data changes to lead to huge ranking changes. In science, this has a name: "chaos".