Like Stakatacool said, before Generation four, Physical and Special attacks were determined by type.
However, there IS a way to see that in-game. (FireRed, LeafGreen only)
You must use the bumpers. (L and R buttons) When you press either bumper, a list of hints, and useful questions and stuff pops up. Choose: "What does this term mean?" and select ATTACK or SP. ATK.
It'll show you a list of the Physical types or Special types, depending on which you chose.
Source: I just tried it on my GameBoy Advance SP
I don't know if it works for the other systems, but it should.