I think the 80 hours refers to patient care, although educational activities like grand rounds are likely included because they are part of the day. I think if you are doing research you can do whatever you please, but if you are also doing patient care at the same time, I'm not sure.
It isn't just a strict 80 hour restriction either - there are limits on consecutive duty hours (I think no more than 24 hours plus a few for "continuity of care") plus there are requirements for number of hours off between shifts (have to have 10 hours off, I believe). I honestly haven't paid a ton of attention to it because it doesn't affect me. But it has affected pathology in that you can't be on call for an entire weekend because that's against duty hours. So people are on call here for 24 hour periods.