Nowadays the Internet is configured with a space for social events, where people portray reviews, build knowledge and interact continuously. This environment provides a channel for interactive media, able to connect companies and their customers in a two-way street. The main objective of this work is to raise from the consolidation of this new Internet era, known as Web 2.0, and the formation of virtual social networks, opportunities for marketing and communication. Further on, other objective of the work is the identification of possible challenges to which companies should be mindful of at the environment of social media. The social networking site Orkut has served as the backdrop for this work, a qualitative study, based on observation of the performance of the companies of mobile operation in Rio de Janeiro: Claro, Oi, TIM and Vivo on this site, and content analysis of texts published in communities and virtual discussion forums. The results of this work suggest that the digital social networks does not seem to be being used to its full potential for the actions of marketing and communication. It also indicates that companies have as main challenges in social media: continuous observation of the manifestations of the groups, the classification of interactions proposed and the use of viral marketing. Suggestions for future research are part of the final text.