We have created a couple of libraries to help you write client applications that access the CommonSense API. There are different libraries for different platforms and languages. The libraries are open source, so feel free to incorporate them into your own app.
Each supported library provides an abstraction layer that lets you construct queries for CommonSense and use response data without having to create HTTP requests or process HTTP responses by hand. Some of the client libraries also provide classes that correspond to the elements and data types that the API uses.
The libraries for iOS and Android are a special case: they also give you easy access to the sensors on the phone. They contain everything you need to build a context aware app.
Use caution! These libraries are still under heavy development, or might lack documentation.