Google's social network is popular in Brazil and India, but other social networks are trying to steal the crown. A ComScore report shows that "in August, Orkut's unique visitors in India dipped by 800,000 within a month, from 16 million visitors in July to 15.2 million visitors in August. On the other hand, Facebook grew its unique visitors in India by 700,000, from 7.5 million visitors in July to 8.2 million visitors in August."
orkut has never been an innovative service: many of its features were copied from other social networks. orkut's popularity in Brazil and India is probably the only reason why Google didn't discontinue the service.
Update (October 29): The new version of orkut, built using Google Web Toolkit, is now available via invitation. "We've concentrated orkut's principal actions onto your homepage, making it a one-stop-shop for nearly everything that you'd like to do. Now you can chat, watch videos, and browse and search within your full friends and communities lists without ever having to open a new page." Check orkut's blog for more information.
{ Thanks, Carlos. }