Schumacher used a row of rev-LED's in the his helmet already last year. Just in his sight they appeared as little flashes, not disturbing or taking away attention off the track but just enough to know where his revs where going.
This year both Ferrari-driver use helmets wich feature two boxes placed left and right of the chin. I am searching every where I can to find out what they do but I haven't found the answer yet.
Some sources guess it's a voice controlled operating system, others mention some sort of head up display.
The problem with a head up display is that it has to be projected onto something transparent in the sight of vision.
I don't think the usual visor of the helmet is suited for that and it doesn't seem to be changed by both Ferrari-drivers.
I more or less expect them to use a little piece of transparent material placed in front of one eye, just like Apache-pilots have this little green square piece of glass attached to their helmets.
Off to search some pics to clearify my miserable English visually ...
Regards,
Dino IV