It (Macrowikinomics) explores how some companies in the early 21st century have used mass collaboration (also called peer production) and open-source technology, such as wikis, to be successful. According to Tapscott, Wikinomics is based on four ideas: Openness, Peering, Sharing, and Acting Globally. The use of mass collaboration in a business environment, in recent history, can be seen as an extension of the trend in business to outsource: externalize formerly internal business functions to other business entities. The difference however is that instead of an organized business body brought into being specifically for a unique function, mass collaboration relies on free individual agents to come together and cooperate to improve a given operation or solve a problem. This kind of outsourcing is also referred to as crowdsourcing, to reflect this difference. This can be incentivized by a reward system, though it is not required.
So I'll be buying the book and I'll give you my review when I finish. For the meantime here's an interview of Don Tapscott:
UPDATE: looks like the reviews on Amazon are a bit depressing, so maybe I won't read it.. Seems like the book is really long and convoluted. Perhaps best to read the wikipedia entry and watch the videos.