I read this book in December and it's still on my mind. Groundswell (amazon link) by Li and Bernoff provides a framework for understanding social media (wikipedia definition). The main idea is that instead of the marketing models of the early broadcast radio and TV days - push advertising out to mass markets, get response, make money - that we must modify our approach to suit the advent of demand-driven consumerism.
The concept of the "Groundswell" is a product of our current level of connectedness via the Internet. Like word-of-mouth on steroids. This is an interesting extension of the writings of Seth Godin and Malcolm Gladwell. I'm intrigued by the idea of demand bubbling up from groups of vocal consumers - shaping products and even companies over time. This represents a fundamental change in the typical opinion of market demand (and research) for my industry. Most direct marketers will tell you "focus groups are crap" and "customers will tell you what you already know." On one point most marketers agree: the proof is in the purchase decision. But the Groundswell may very well give us a completely new way of genuinely listening and learning about the marketplace.
The most important and practical things to take away from this book are 1) doing an accurate assessment of your customers and prospects' online behaviors, 2) understanding the importance of responsiveness in Internet communications, and 3) how powerful honesty and transparency can be online.
1.) Figuring out whether your customers and prospects are active Internet users is key - you have to go where they are. Also, identifying key customers (i.e. product evangelists) who might generate online content about your products (good or bad) can be a powerful first step.
2.) Create a workflow that responds to online inquiries in a timely and logical way. Auto-responders do not count (these are merely a receipt of transaction, not a response). Respond to complaints honestly, quickly, and respectfully. You will be surprised how word "gets around" online about customer experiences.
3.) Be honest and show your customers what you are doing to improve or enhance their experience with your company. Share information and ideas using internal and external fora - yours or an existing one.
For Business-to-consumer marketers, Groundswell has particular relevance. I found the book very meaty. Even if you don't need the complex analysis and framework (thank you Harvard Business School) presented, you'll find this book worth reading.