Take a look around the Google Search Results page, and you'll start to notice some new items Google has been adding to the page.
One of these new features is a notation if Google is customizing your search results - giving you different search results than anyone else.
A message will appear in the top-right corner of the search results page, with a link to a page with more details about how and why Google personalized your search.
As long as you are logged into your Google account, Google will generally give you unique results based on geographic location, another recent search you performed, or items from your Web History.
Google Personalized Search gives your own unique search results only when you are logged into your Google account. Previously, you never knew when you were getting customized results since it was all done behind the scenes. Now that has changed.
Make sure you are logged into your Google account while Google searching so that Google can to learn how you search. Pretty soon Google will begin to give you more relevant and useful search results.
More about understanding Google Personalized Search.