According to a recent post on lists.blender.org Valve is allegedly looking to integrate Blender, the free 3D modeling software into Steam! The possibilities here are endless! Model something in Blender, click a button and *POOF* your epic nacho sombrero is almost instantly available for everyone to use in Skyrim!
This seems like a really logical step for Valve when you take a look at their history. They are a company built on mods and mutations and evolutions. The original Half Life game was built on a modified version of the Quake engine. Both Portal games were based off of student projects.
It appears that Valve is just probing the Blender community for interest at this time and nothing is concrete. So for right now we can do nothing but keep our fingures crossed, kick back, relax and play yet another round of Left 4 Dead 2 because nothing builds anticipation like surviving a zombie appocalypse!