source... president Satoru Iwata appeared in a video. He stated that the company now officially gives its permission for anyone to use their properties for derivative works – Let’s Plays, music covers, fan art, and more were specifically showcased.
Additionally, Iwata announced a “Creative Endorsement Program”. This will allow Nintendo to provide revenue to creators who produce well-received work. At the moment, this program is only available on Niconico, as it is a subsidiary of Dwango.
I remember a few months ago Nintendo went on a flagging rampage on YouTube, so hopefully this means no more of that. I wonder if it also applies to fan games (like Mother 4) too?