Google updated a lot of there services like Google Search and Google Earth with a new look. Here is how it looks now:
They also have it available for Gmail. Here is a quick way to enable these cool new look.
Go to your Gmail account and log in. In the upper right corner click on the little cog and go to Mail settings.
Click on the Themes button at the top.
Then select any of the two with Preview in there name.
There ya go easy as that
This is really cool!!