WebmasterWorld founder, Brett Tabke asked in a WebmasterWorld thread;
I think I have been logged into Google when I hit google.com before and gotten the "classic homepage".
Today, I just went there and I got my personalized Google page as the http://www.google.com homepage.
Have they been doing this for awhile?
As far as I understand it, if you recently visited Google's Personalized home page and then went back to Google.com while signed in, Google will always take you back to the Google Personalized home page. The only way to get back to Google.com's main search page, while logged in, is to click on the Classic Home link, and Google will remember you want the Google.com results. That is until you click back on the Personalized home.
Forum discussion at WebmasterWorld.