Gmail has formally launched the feature of theme replacement (from Gmail official blog entry: Gmail Themes), totally of 30 fairly good themes. And they can be changed according to different locations and weather. The following is only the part Google Operating System listed before:

Compared to Gmail, Windows Live online services (except for Live Events and Live Spaces) will adopt a unified theme settings to Windows Live wave3. New theme also includes styles similar to Gmail. Screen shot of the interface of theme settings is as follows:

You can click the following picture to view several major theme backgrounds of Windows Live wave3:

(The above two photos are from the entry: Windows Live Wave3 新主题风格欣赏. Thanks to LiveSino.net)

Of course, the various icons of the Windows Live new products are aslo charmful. Here is the picture of design style of these products.