Solid-state disks (SSDs) are already trickling out from various manufacturers, and you can even order them as an option on some laptop systems (notably, the Asus EEE comes standard with one!). The advantages over traditional hard drives are obvious: speed and power consumption, though of course the former is somewhat limited by the system bottlenecks. Capacity remains the major hurdle, though – state of the art is presently 128 GB (which admittedly is 50% larger than the hard drive on the laptop I am writing on now). And of course cost – which probably scales as the fourth power of capacity (call that Fledge’s Law).