The BBC recently published a rather lengthy article via its website where they take a look at the rise of the handheld console in gaming. Of course, the piece focuses on both the PSP and DS, their goals and market share they both enjoy. And, focusing on the DS, the piece looks to the Touch! Generations line of games as being the driving force behind the incredible success the DS has enjoyed both at home and abroad.
The article is a little hefty on the PSP stuff, though mostly due to the failed promises made by Ken Kutaragi for the device. Still, it's a good read for any handheld gaming enthusiast.