In the past, Yahoo has always kept their logo at the front and center of their homepage with the search bar located right underneath. This is the way it was every since they launched until they changed it back in 2006. At that point they unveiled a completely new design that moved their logo to the upper left corner of the page. It looked nice, but apparently they’re more comfortable with the logo in the center because they just made an adjustment and moved it back to the center. The image below shows you the “old” homepage that was used up until recently (logo on the left) and then an older homepage screenshot from 2006 before they launched their big redesign. Then of course there’s the new screenshot of what Yahoo looks like today:
To me, it seems like there is now more emphasis on search with such a large search box spread across the screen. Other than moving the logo and the search box, nothing else has changed and all of the information that was previously available is still there.
Source: Google Blogoscoped