Why would a business want to get involved in social media? By nature, it is unpredictable as we human beings naturally are, and that can be scary.
At the Connections '08 conference for users and agencies that I attended in September, ExactTarget selected "Subscribers Rule!" as the theme. What does that mean? You can read Exact Target's exact definition here. ExactTarget is in the business of email marketing, so they want us to think about the needs of our email subscribers and how to keep them happy. You want to give them control, to let them "Rule" over how you communicate with them. For example, you allow subscribers to choose to get your emails instead of sending them unsolicited spam, and make sure to send them content that fits their interests.
In the early days of my web design and development career, which started 11 years ago, I encouraged clients to make it as easy as possible for customers to contact them by providing information about multiple means of doing so, such as telephone, fax, mailing address, and email. Different people have preferences for how they like to communicate. I for example, am very comfortable sending email but don't enjoy talking on the phone. A company that provides an email contact is much more likely to get my business than one providing only a phone number.
According to the ExactTarget 2008 Channel Preference Survey, the trend is for younger consumers to place less importance on email as a communication channel than older consumers. This does not mean that email is going to go away any time soon however. Among the youngest age group in the survey, 15-17 year olds, email is still the second most favored channel. All of the other groups surveyed showed email either tied for first place or in first place. And since you need an email address to register for many services, people will still need to have an email address even if it isn't used as the main form of written communication.