The service seems to have been hit by a worm named Bom Sabado.
It creates a major mess on user profiles as it scraps the text ‘Bom Sabado’ on profile pages.
You visit an infected profile page, you are likely to get affected as well.
Google has not yet made any official statement on this issue but we expect them to be working very hard on it.
Avoid using Orkut for now. And if you have been hit, change your Google Account password asap!