The following was posted at the official SEGA blog…

For many weeks now all of you on the forums and the blogs have been asking us to make good on our promise that we were extending the development of the game to make it even better. Today, those of you with a quick mind will begin to spot the fruits of that labor, which our teams have been hard at work on.

But the good news doesn’t end there. After a poll conducted on the Sonic 4 forums, we have decided to begin releasing additional information about the other changes we’re making to the game directly to everyone in the community, which will be posted exclusively here on the SEGA Blogs and the Sonic Blognik!

To further that excitement: the first blog listing some of these new changes will be arriving tomorrow. We’d like to think that this sound effect just started playing somewhere.

Link

What’s next in the Sonic 4 pipeline? Beyond today’s screenshots and details of more changes, we also plan to show you what Lost Labyrinth looks like in action soon. We hope you guys are pleased with today’s update, and that you’ll join us for the rest of the run towards launch. There’s still much more to come on the Sonic 4 front!