No, I don't think so. Superlatively it is important to note what social networking is.
A social networking service is an online service, platform, or site that focuses on facilitating the building of social networks or social relations among people who, for example, share interests, activities, backgrounds, or real-life connections. A social network service consists of a representation of each user (often a profile), his/her social links, and a variety of additional services. Most social network services are web-based and provide means for users to interact over the Internet, such as e-mail and instant messaging. Online community services are sometimes considered as a social network service, though in a broader sense, social network service usually means an individual-centered service whereas online community services are group-centered. Social networking sites allow users to share ideas, activities, events, and interests within their individual networks.
Actually, the aim of this social networking is connected with a lot of advantages. Through an individual profile, people can explore the things and to know about what's happenig around. Facebook is one such example. It is a popular social network which people make a lot of advantages. For instance, if one is away from home, there's possibility of sharing photos instantlt, status, chatting, pages and news updates and updates from loved ones. It's very easy.
And about what you asked, I don't really think this has harmed the art of face-to face conversations. People meet in need no matter how close they feel with these services. Yet their is video chatting and services which makes things easier. Still I don't believe face to face meetings do not happen due to social networking but I think there's more possibility of wanting face-to face conversations with the new people (if needed) we get to know in facebook, twitter etc.