Hi,

Based on my understanding, to maintain your Login name accessible throughout all your application, you can use a Shared Service to store it instead of passing it through navigation. Therefore, this Shared Service will be referenced in your application Modules so they can access the info stored in it. For more information about Shared Services, you can go to the following section of the Prism documentation:

• Chapter 9: Communicating Between Loosely Coupled Components - Shared Services
  

I hope you find this useful,

Federico Martinez
http://blogs.southworks.net/fmartinez