A guy named Gistix and his team are apparently recreating Sonic 06 in Unity on PC, starting with the original demo's content. Speaking of the demo, it appears to be largely based on the demo's physics, animations, and other such things. It's highly impressive work, matching nearly 1:1 in terms of gameplay and attention to detail, from what I can gather. I believe he said a demo will be appearing at this year's SAGE, and I'm looking forward to getting my hands on it. Thoughts?
EDIT: It goes without saying that 06 was obviously a bad game and the way this is going it won't exactly be a huge improvement. We have very little to go on right now, other than the one stage, and I think the work it took to get this functional is extremely impressive in itself.