I saw in @codinghorror’s post that this wants to be the WordPress of discussion forums, including adopting their business model. This was linked to a page of “how to build a business around WordPress”.
Unfortunately, WordPress (and Drupal) believe that all plugins and themes, including images and CSS fall under the GPL as well, since they use the WordPress API.
This makes it essentially impossible to make a living (legally) selling WordPress themes and plugins, and pretty much every “business model” in the linked post is against WordPress’s interpretation of the GPL.
I don’t believe that WordPress has sued anyone yet, but they have started banning prominent WordPress-based businesses from participating in their conferences.
This article has some more depth on the controversy.
Personally, I feel that WordPress is using the GPL to poison their community, rather than encourage businesses to be built around it, and I don’t want to invest a lot of energy in Discourse, or encourage others to do so, if they truly are following the WordPress school of business.
My question to the owners of Discourse: how do you specifically interpret the GPL when it comes to themes, plugins, and associated media? And could you clarify this, for all time, somewhere on the site, so that people can know where you stand on this?