In this article, Mahesh Sabnis explains how to use the Prism Event Aggregator mechanism in Silverlight applications to communicate between two views of different modules.
Source: Dot Net Curry
Now-a-days, I see many Silverlight 4 developers using Prism 4 UI patterns for enterprise application development. Prism 4 is a nice framework for developing applications based on a modular approach. I have already published a series of articles on Prism 4 on Prism Basics, Modularity, Events, Commands and Custom Behavior etc. One of the nice features of Prism 4 is that you can very easily build End-to-End applications using either WPF or Silverlight.