Yes they can! I prefer to have my iPod Classic PC formatted for one reason only and that is so I can copy my songs back to the PC when I wish. If the iPod is Mac formatted, my copying program can't read the iPod to copy to the PC. I can use the PC formatted iPod 100% with the Mac and it syncs just as if it were formatted on the Mac. Only drawback with this is that to do firmware updates, I have to do them on the PC this way.