Groundswell: Winning in a World Transformed by Social Technologies. This book is a great primer for social media. If your new to social media this book is for you.
However if you have been working with blogs and wikis for more than five years this book is a bit too elementary but a great quick read nevertheless.
The Groundswell is the powerful movement of our networked society. Basically the book breaks the “groundswell” into gaining insights from what social networks say about your company, your products and the people representing your company.
We have reached a point on the modern internet that personal voices will grow via social media tools never before available. This will help to drive new marketing plans, business reach to both existing and new customers. This can drive new media to tell stories about products and community movements.
Blogs help talk to your communities, and buzz helps energize the groundswell and the new ability to utilize “customers” as collaborative team members. In the end its Groundswell is about person to person relationships.
Beyond his sheer volume of knowledge regarding the economy, global markets and international finance I was most impressed with Greenspan’s simple yet immense observation: America needs an overhauled 
