Over the last couple of weeks, Google launched a couple of interesting search experiences: one for the Beijing Summer Olympics (what an Olympics!), and one for the upcoming U.S. Elections. Each of these sites has a Custom Search box on the top right corner that promises to make it easier for you to find relevant information fast!
Search for "bolt" on the Olympics search engine, and then on your favorite web search engine. One gives you a big Bolt smile, while the other will likely give you a page with little to do with Usain Bolt. Context!
(Note: try it today, as this behavior will change in the future with web search updates)
Try searching "roe v wade" with the Elections search engine and on your favorite web search engine. The first gives you John McCain and Barack Obama's positions on the issue. The other ... general information. Context!
My point? Context does make a big difference! That's why I'm a big believer in search personalization as well...