Yes, I think that social networking has had bad effects with human beings and how they interact socially with each other. All too often it seems as though humans would rather be on Facebook or Twitter rather than hanging out with real friends which has dentrimental effects to how humans socialize.
Social networking sites can be a positive or a negative aspect to life depending on how you use it such as many other areas like alcohol, wealth, or food. For example if somebody enjoys alcohol in moderation it can be a positive addition to their life that enhances their social life, whereas someone who abuses alcohol will have many problems. In terms of social networking it can be used to spread awareness of a business, keep you connected with people you'd otherwise lose touch with, or allow you to quickly share your favorite music with your friends. On the flip side when people spend too much time on it they can start to use social networking to replace real life human to human interaction.