Yeah, it depends on the specific components. I use SRAM chains and cassettes all the time with shimano derailleurs. I also have Campy shifters with a Shimano drivetrain on one bike. Campy 10 speed shifters just happen to work on 8 speed Shimano drivetrains.

Other Campy-Shimano combinations function as well by utilizing various work-arounds and conversion do-dads. Campy and Shimano aren't designed to work together though.