Describing how and how not to utilize microformats is what John Allsopp accomplishes in this book. For the first book to address this technology, it is extremely effective. Utilization of microformats is still somewhat of an art at this point because of its interaction between presentation and encoding of information. The premise that the book brings out is that microformats are designed first for humans and then for machines.
Allsopp starts with theory and moves quickly into practice. The book enumerates the current crop of microformats like hCard and hCalendar with a good deal of discussion about Web sites that employ these. It also includes a sufficient amount of history.
Allsopp justifies the usefulness of microformats in that they are primarily designed for adding meta-data and improving machine interpretation of data. That makes it easy to do things like copy an address card from a Web page using browser extensions. New versions of browsers will incorporate microformat interpretation and use it as part of their standard support. This could be important for embedded developers as well since extraction of data from a remote device is a typical chore.
Developers looking to utilize microformats will find this book invaluable.