I do; I don't want to have to turn off my phone every time I go to class; I put it on vibrate so I can tell if I got a call at all, then check my "missed calls" list to see whether or not i should call them back.
I wouldn't trust firefly's list either, that seemed to be more of a wish list than anything. However I do think they're going to have a vibrate function. I mean, how could they not? And its not like vibrate would be so hard to build in. If it were, every cell phone in America wouldn't have vibrate.