Matt Stauffer gave a lightning talk at NomadPHP on how to upgrade from Laravel 4 to Laravel 5:
Changing major versions of a framework can be a daunting task, and the Laravel 4 to Laravel 5 upgrade path has had a lot of people talking lately. We’ll take an open-source Laravel 4 project and walk through the steps to convert a Laravel application from 4 to 5.
He also a written tutorial on this available on his site.
Lightning Talk: Upgrading from Laravel 4 to 5 is a post from Laravel News.