So all the while everyone’s been focused on Google Caffeine and what their results may look like after the rollout “after the Holiday season, to save webmaster stress” Google have been chuckling away to themselves knowing that, that’s not what we need to be worrying about at all.

What we didn’t know is that they were going to quietly put live with no prior discussion, warning or concern about “webmaster’s stress” at all..

The most important single change to the index since the Big Daddy update..

Personalized search is now STANDARD, as in “Opt-out” for EVERYONE

Announced suddenly on the Google blog here

Today we’re helping people get better search results by extending Personalized Search to signed-out users worldwide, and in more than forty languages. Now when you search using Google, we will be able to better provide you with the most relevant results possible.

For example, since I always search for [recipes] and often click on results from epicurious.com, Google might rank epicurious.com higher on the results page the next time I look for recipes. Other times, when I’m looking for news about Cornell University’s sports teams, I search for [big red]. Because I frequently click on www.cornellbigred.com, Google might show me this result first, instead of the Big Red soda company or others.

Previously, we only offered Personalized Search for signed-in users, and only when they had Web History enabled on their Google Accounts.

What we’re doing today is expanding Personalized Search so that we can provide it to signed-out users as well.

This addition enables us to customize search results for you based upon 180 days of search activity linked to an anonymous cookie in your browser.

It’s completely separate from your Google Account and Web History (which are only available to signed-in users).

Leaving aside the Privacy Issues for a moment, the SEO significance of this is HUGE, we’ve mused about a year ago about the “rankings are dead” chorus, but here we actually are..

Personalized search for EVERY USER..

..Meaning EVERYBODY SEES DIFFERENT RESULTS

As always, the most comprehensive discussion on the subject is on Webmasterworld HERE and you’ll be able to see exactly how much “stress Google have saved webmasters over the Xmas season” over there

This has so many implications going forwards, SEO will never be the same again..