The first thing companies often want to do to “jump in” to social media is start a company blog. They put together a nice-looking page, build a sidebar of links to their site (ahem, perhaps try linking to other sites too), and write a few helpful posts. Within a few weeks, I usually hear ‘Why aren’t we getting any comments?’
Well, let’s see. Do you read blogs? (I hope the answer is Yes, because if not we have a lot to talk about!) Assuming you read blogs, and quite a few because there is lots of great content (get thee an RSS reader!), do you comment on blogs? How often? What kind of comments? (ie, are you actually contributing to the conversation or saying things like ‘Hey yeah, me too’?)
In order to “do” social media, you have to interact. And no matter how good your SEO or how big your brand, no one is going to know you’re available to interact until you find the people already in the space and initiate a conversation.
Assuming you’ve done a basic social technographics profile and determined that blogging is a good way to reach your audience and that your target base contains a decent percentage of Creators and Critics, the only reason you’re not getting comments should be that the people you’re trying to reach haven’t found you yet (unless commenting is unduly difficult on your blog—such as requiring a registration. Try leaving a comment on the blog from a computer outside your office and make sure it’s super simple.). Reach out a little, and the people you touch will help more people find you along the line. I believe in inbound marketing, but I never promised you could literally just sit back on your butt and watch the sales roll in!
(If the first part of the last paragraph sounded like scary gibberish to you, you haven’t read Groundswell yet! I recommend you do that before embarking on any of this, especially if you think you’re just going to “get your feet wet” and don’t really understand how social media can help build your business.)
If you don’t know where exactly to jump in—or worse, read very few (or no!) blogs— start by asking existing customers, coworkers, your marketing team, your friends, and anyone you can get ahold of what they read online. Most of those sites will lead you to other places… and then you’re off!
An additional great tip for learning about improving your blog: listen to or particpate in #blogchat on Twitter, which happens every Sunday night at 8:00pm CST. If you have no idea what I just said, shoot me an email and I’ll introduce you to some Twitter basics. 
This is too true and applies to non-corporate blogs too. Especially on newer sites, I find that the majority of incoming traffic can come due to referalls from comments left on other blogs.
Certainly the “build it and they will come” approach does not work here – great content alone is not enough to engage your online audience.