I think it depends. I mean, we're not expected to know much at all, but I wouldn't say we're expected to know "nothing." I definitely have had attendings during my first month and a half who have point blank treated me like I'm making the diagnosis. I mean, if we get it wrong, which obviously we are going to be many times, it's a learning opportunity and no one makes you feel bad about it. It's generally unacceptable to sit back and not try. I have learned the most from attendings who make me sweat it out.
To more directly answer your question, it probably varies by program. Here, in general, we are expected to know the clinical history, be familiar with the gross findings in each case, know normal histology, patterns of injury in each tissue, and most common disease processes and neoplasms associated with each organ system. In terms of frozens, we get trained and help is always available; we're responsible for receiving and grossing. If on call, we accession, gross, cut, and stain.
In terms of grossing...well, it doesn't take long to get used to general grossing skills and some specifics, but it takes longer to become familiar with gross-histologic correlations.