Saints Row developer Volition is providing official modding support for Saints Row: The Third and Saints Row 2 as a "test run" for Saints Row 4, according to a blog post on IdolNinja.com.
According to the post, Jeff Thompson, Volition's studio manager of programmers, will work with modders over the next few months to provide documentation and mod tools for the most recent two Saints Row games. The modders plan to create a "robust set of modding tools to supplement our existing ones ... creating what is essentially a full SDK for the game," the blog post reveals.
"So, what does this actually mean to the average Saints Row player?," the blog post asks. "In simple terms, the modding community will finally be able to create and offer new clothing, new vehicles, new guns, new NPCs, new missions, and even new world geometry which will greatly extend the life of the series and enhance the Saints Row games in ways we never even dared to dream of."
IdolNinja also revealed that this is happening because he asked and Volition accepted.
You can check out a collection of Saints Row mods here and Polygon's impressions of Saints Row 4 from E3 2013 here.