Check out the update on the twitter blog, here.
Co founder Biz Stone stated that:
"We've added a few other features to this design. If there's a search you want to do on a regular basis, you can "save" the search. That will place the word or term permanently in your sidebar for easy access. So if you want to know what people are saying about the city you live in, the products you use, or just something weird, it becomes a link on your home page.
Twitter Search is an engine for discovering what is happening right now but it doesn't always have to be a box and a button. Trends are words or phrases being referenced with more frequency suggesting that something interesting might be happening. When you click on a trend link, you can read the tweets and find out what's up. Trends is in beta—but it has potential."
