I went to the Bodies exhibit at the Luxor in Vegas a few years back. It's pretty cool stuff, would totally recommend anyone going.
I went last month. It was pretty amazing. I'd consider the skill involved in the disection a form of art.
People sign off to have their bodies donated for science. Whether it's this, or every anatomy lab in universities around the country, they sign off on it beforehand. And the relatives have the ability to take the body back at any point in time afterwards if they have second thoughts.
I went to Body Worlds at OMSI a couple of years ago. It was interesting and kind of gross at the same time.