Source: http://googleblog.blogspot.com/2007/...-speaking.html

Quote Originally Posted by Google Blog
Today, we're taking another step toward making personalization more available to you by combining these two into a single signed-in experience. Now, when you're signed in, you'll have access to a personalized Google—one that combines personalized search results and a personalized homepage.

Keep in mind that personalization is subtle—at first you may not notice any difference. But over time, as the search engine learns your preferences, you'll see it. For example, I (Sep) am an avid Miami Dolphins fan (no joke). Searching for [dolphins] gives me info about my favorite football team, while a marine biologist colleague gets more information about her salt-water friends.