that is in front of the driver between the guages. From the pictures I have seen it looks like an air vent but it is up in the windshield and can actually be seen from the outside pictures.

http://images.rotarynews.com/images/RX-8Tokyo/ascii24-08.jpg

That thing on the top, in the middle of the dash? I think that may be a center speaker.

Yeah, it kind of looks like a speaker to me too.

I agree on the speaker assumption. It isn't big enough to be the windshield defroster/defogger. Please let there be a kickass sound system.

This is no speaker, but from the picture posted above I see what you are refering to and yes that looks like a speaker to me as well.

http://www.mazdausa.com/images/rx8/gallery/rx8_pop12_1.jpg

Here is a front view where you can see it through the windshield.

http://www.mazdausa.com/images/rx8/gallery/rx8_pop01_2.jpg

That's the older version of the RX-8, anyway, I have no idea what it is.

That semicircle thing? That looks alot like a HUD (heads up display), which im sure we wont see in a production a model. I cant be sure, but I saw something alot like that in a concept car here at the Portland auto show. Had speed and RPM on it right there in youre field of view so you wouldnt have to glance down. Really not a bad idea if you think about it.