I don't understand about pokewalker, is it a device?
It's a pedometer gadget, you can see a picture of it here: http://pokemondb.net/pokewalker (it's about the right size, too!)
It's a real physical thing so it's 'hardware'. (Software would just be something in the game itself, like the Poketech from Diamond/Pearl.)
Yes it's hardware. It's PokéBall-like designed pedometer