At today's Vision Summit 2016, Valve's co-founder and managing director Gabe Newell appeared by via video address to announce that Valve and Unity will be adding native support for SteamVR to Unity, for free.
"We made many of our Vive demos using Unity, and continue to use it today in VR development”, Newell said. "Through that process, and in working with VR developers, we found some opportunities to make Unity even more robust and powerful for us and really want to share those benefits with all VR content creators."
Unity CEO John Riccitiello echoed Newell's sentiments: "Valve and Unity are both dedicated to creating the highest quality VR experiences possible. That means giving developers every possible chance to succeed, and our collaboration with Valve is designed to do just that."
Newell also had a surprise for the audience: every developer in attendance would be taking home a Vive of their own. Here's the video of that announcement: