Well the 3 left buttons in the header links change on how you use the site. For example, those three buttons for me are "Groups", "News" and "Finance". If I sign out, they become "Finance", "Music" and "Shopping". I can also hard code them to specific features.

Since Yahoo! is my homepage I very much like the changes and have already made sure I am in "Beta" mode so I get the updated page. Will make things a lot easier in the future. Loads faster as well.

It will be interesting to see how they integrate MusicMatch and the idea of selling songs online into the homepage and how they market against iTunes and Napster.