I am really happy to hear that you're getting excited by the concept of social media. There's no question that the principles of social media—in short, embracing a candid and ongoing dialogue with users—constitute an unstoppable trend.
Meanwhile, the tools of social media (blogs, Twitter, Flickr, YouTube, etc.) are becoming ever more important components to the marketing mix.
The fact that you want to get personally involved bodes well for your company's chances of successfully navigating these unknown waters.
I can understand why you, as a CEO, would be interested in "joining the conversation." It's an interesting conversation: After all, it's a conversation about topics of interest to you and to your company, and the people you'll interact with will self-identify themselves as being interested in what you've got to say.
And, for what it's worth, here's some more good news: It takes a lot of talent to rise to the CEO spot; you need to be confident, charming, smart, and articulate—and these are excellent qualities in a blogger, too! Done well, your foray into blogging will afford you both personal satisfaction and bottom-line results. So we're off to a good start.
So, umm, how do you really start? How do you get started blogging, and do it well? Let's avoid the technical requirements (you're the CEO, you've got people who can figure that stuff out!) Instead, let's focus on creating the right mindset.
First off, you need to explore your motivations and time commitments before you consider a dual career as a CEO-blogger.