Sites such as Linkedin greatly expedite the recruiting process. Employers just search for keywords and find many possible candidates. They no longer need to call someone to find if they know any possible job matches. "Using Linkedin, Steckerl says he can scout a group of job candidates in just half an hour. But if he wants to develop a relationship with any of them, he says there is no substitute for a much older social networking tool: the telephone." So there are still things that such social networking sites don't replace. But for users of more social sites like Facebook, people don't really need to talk on the phone, they can have whole conversation on walls, comment sections, or through messages.
These technologies can change the way that we look for things online. Facebook wants to be the future of the internet. It has a different way of thinking than Google. If either wins, people will get used to their way of thinking and searching. Social networks make accessing people easy. Someone can find out a lot of things about someone on sites like Pipl.com. Everything a person has online; pictures, history, thoughts, etc, is accessed and brought together.
Facebook brings people together, but it also separates them. Some people live in social networks and do not use regular means of communication. Phone conversations might eventually cease to exist as all communication will be via computers or whatever new device comes out.