Valerio Riva gave a presentation on developing Unity3D mobile plugins. He discussed extending Unity for iOS, Android, and Windows Phone 8 by creating C/C++ libraries that can be called from C#. He provided examples of creating a Flurry analytics plugin for Unity, including wrapping the Flurry SDK for each platform. He also covered best practices like running code on the correct threads, faking plugins for the editor, and hiding complex classes from Unity.