Project Spark is coming to PC, Xbox 360 and Xbox One, but specifically, a member of developer Team Dakota has stressed that you won't need an Xbox Live Gold subscription to play the Xbox One build.
I'm guessing this also applies to the Xbox 360 build, but developer Mike Lescault was speaking only about the Xbox One version in this Reddit thread.
I've been thoroughly impressed with Project Spark so far. Check out my latest time with the game creation suite here. The Kinect mo-cap feature is particularly brilliant.
What do you think?