fishfinger - 10:46 am on Oct 31, 2006 (gmt 0)

My view is that it is just coincidence.

One of my longest affected sites has "brighton" in the domain name and is optimised for "brighton", "west sussex", "uk". Others have always been optimised for "london", "kent" etc etc.

As far as changing content goes - two other affected sites dynamically update content every visit to the page.

Tweaking won't change anything. But it's always good to look at your site and ask yourself if it could be better though :)