Well, actually, Google is all about the advertising, but that’s another article.
From the Twitter blog:
We went back to the original sketch and made everything far more awesome. Currently, a small subset of Twitter users are trying this new search feature in the sidebar of their Twitter home page. When you do a search, you don’t go to another page, the relevant tweets instantly show up where you’d expect them to—right on your home page where tweets love to be.
Take a look at the whole article. It’s awesome to see the design process boiled down to a simple sketch on a legal pad. Sometimes, the best ideas have very simple beginnings.