Well for one, most traditional marketing activities merely circle the target instead of actually participating one to one with them.
Here's what I mean:

See how the activities simply rotate around the customer? But never actually get any closer or touch them?
Now look at social media:

A web audience is "tuned in". Meaning that they proactively SEEK OUT, SHARE, AND DEVELOP content. Do not ignore these possible brand advocates or brand haters. Respond to blogs, tweets, etc. the very same way you would a customer service call - in fact that department is likely the best qualified group to handle online grievances as they have already been trained to avoid any actions that are not permitted by your organization.
But I will say this - there is nothing more powerful than leveraging your highest ranking officials in this capacity as well.
The key is LISTENING.
Here are two simply tactics for listening:
Set up Google Alerts
They'll find your company's name whereever it's being used and serve up links to you in the frequency you specify.
You should also monitor tweets. For this, I recommend TweetBeep.