hidden content

i have many div elements wich are hidden and made visible with javascripts

is this content visible for google and co?
is it maybe cheating for google & co?

Only if they are full of keyword spam. I wouldn't do to much of that though as you never know with Google and the rampage they're on these days. But I doubt they will even blink at normal stuff. Heck, they would have to ban all their own sites if that was the case.