Here is the first post of a new series called "Windows Phone recipes". The Nonlinear Navigation Service is the first recipe released by Yochay Kiriaty.
Source: The Windows Phone Developer Blog
The main reason we are introducing the Nonlinear Navigation Service is to address a common pattern in Windows Phone Silverlight applications, where a given application has a circular path (also known as a loop) in its page navigation. Loops in an application navigation back-stack can be defined as “duplication” of specific pages in the application back-stack. The Windows Phone Silverlight application model uses pages as the building block of Silverlight applications.