One of VMware's senior Cloud Security Architects, Michael Haines, has started a multi-part blog series on using the vShield API.  He has taken the approach of showing how the vShield API can be used in the daily life of a Network and Security Admin.  In his words

In these series of blogs the Network and Security System Administrator will get hands on programming experience with the vShield API and learn how to consume the API in their own programs and applications. The Network and Security System Administrator does not need to be a developer, although basic programming concepts will help them understand the vShield API better.

He has already posted the Introduction, as well as Part 1 and Part 2.  To keep up with the rest of the series (and to learn more about cloud security), bookmark the VMware vCloud Blog.