A Copenhagen artists' collective came up with the idea of open-sourcing the recipie/branding for a new beer. The result: breweries from all over are using and improving on the recipe. Currently they're on batch 3.0, with breweries picking up the pace.
What makes Free Beer free is the same thing that makes free software free: Its recipe is open and licensed freely. Anyone can make improvements. But anyone who distributes an improved version must release the changes as well