If you login to your Google AdSense account you will be prompted to try out the "new AdSense home page."
The new home page revamps the design of just the home page to give it a "fresh new look." The new look is cleaner and more modern, Google says it "focuses on key day-to-day information."
Here is the notification you will see when you login:
Here is a live screen of the home page, you can click on it to see a larger version:
Many AdSense publishers are seeing this now, I suspect you will also.
There is some early feedback in the forums on the new design.
Forum discussion at WebmasterWorld.