Software, unless they are altering the hardware of a pda to add better wifi or something... that stuff is mostly seen in the movies and is very advanced in real life.I hear people who take already made devices, PDA, Ipod and mess around with it to make it better or to "customize it." Or like one of the articles on HTS that talks about "hacking" a psp to get emulators running on it, software or hardware based? I don't understand that either. It's mostly a personal thing for fun.
Yeah, most of the time these so called "hacks" are just that they install a custom firmware. WRITING a custom firmware from scratch, however, is a different matter.