Orkut official blog announced "We recently began rolling out 12 themes to a percentage of our Indian users, and these themes should be available to all Indian users by the end of this week. We're currently testing this new feature, and if we hear that users like it, we plan to roll it out for everyone on orkut and continue offering more new themes.
How do you switch your theme? Click on the "change theme" link in the top navigation bar or go to the"themes" tab in the edit profile page. You'll then see our gallery page, where you can check out all the themes that are currently available. Alternatively, if you visit a friend's profile page and he has a theme you like, click on "get this theme." When you select a theme, all your orkut pages will have this theme: your profile, scrapbook, photos, videos, etc. When other users visit your profile or other pages, they will see your selected theme."
this is official screenshot,
Photo edited in New Windows Live Writer