Hard Drives remain to be one of the slowest parts inside a computer so every bit of extra performance is welcomed, indeed. Notebooks have often used 5400rpm (or slower) hard disks due to power consumption and noise constraints, a few exceptions being those laptops using HDs actually designed for desktops. Hitachi has announced today the 'first 7200rpm hard drive designed for mobile systems', the Travelstar 7K60.
Hopefully we will start to see more advances in this field, as faster drives make it into the high-end notebook market, I wouldn't mind running a 10,000rpm drive at home soon, actually those aren't too expensive anymore (though still $1 vs. $4 per GB make a difference!).