Brett_Tabke - 8:03 pm on May 11, 2010 (gmt 0)

>traffic changes to one single cause

When they tie to a specific event at a specific time - they are quite easy to locate. No change in referrals during the so called 'may update' (we have seen zero change - as far as I can tell - there wasn't an update), and then stuff happens the morning they roll out the new layout. 1 to 1 correlation = causation.

> "Page previews"

yep. But how is that any different than 'cached' page.