You've seen screenshots from the new Yahoo homepage. Now you can try it at http://www.yahoo.com/preview. It's cleaner, oriented to search, there are no ads and the space is used wisely.
The new Yahoo homepage gives reasons to sign in: to get a preview of your new mail or to see your contacts. If you don't remember the name of a Yahoo service (in fact there are so many that no one remembers more than five or six), you can click on "All Yahoo Services".
Note: You can try the new homepage only if you use Internet Explorer or Firefox. So Opera users and Safari users won't be able to access Yahoo Mail Beta and Yahoo homepage.