Orkut currently shows only 4 themes:
and the Classic Blue Theme...
You can also disable the themes if you wish... You will also be allowed to create your own themes and just like Orkut apps these will be downloadable and sharable with your friends. Themes have not been rolled out to all the users, but will take a few more weeks to be shown to all the users. Just like the success of Orkut Apps gave an opportunity to developers, Orkut Themes will give designers a chance to monetize their skills.