Click me to watch teaser trailer
It's a not-for-profit fan film currently in production by Sollar Systems Studies and Eddie Lebron.com. The teaser doesn't reveal much but there's a little more on their website.
http://www.sonicsatam.com/

Sonic for this has been given a complete make over, he has fur and actually hedgehog spikes. A very creative, if brave idea on making the blue guy more real which I hope pays off. He is also going to be voiced by Mr. Jaleel White, I think one of the original voices for Sonic in the anime or game.
I'm not much of a Sonic fan, it was something I was interested in as a kid an the recent games haven't sparked anything for me. However I gotta admit, I'm sort of excited about this, but in the way I am with the Pluto. It might be something really epic, or it might fail. Whatever the case, I'm looking forward to this one and what they'll turn out.
You can find a few more early pictures from their web page here and an interview:
http://www.sonicsatam.com/fanfilm/