In the biggest change to personal computers since the arrival of an affordable 5 1/4" hard drive about 25 years ago, solid state "hard drives" will be appearing soon in laptops. The solid state storage devices have no moving parts, use much less energy, weigh less, are faster, and are more durable.
Laptops will shrink dramatically in size and weight. Weight will go down directly from the reduced weight of the replacement solid state drives, but also indirectly; spinning hard drives are the biggest drain on batteries in a laptop. The replacement solid state memory will allow both smaller batteries and much longer useful work time on laptops.
Laptops will be thinner, lighter, smaller, and faster, and won't cost much more because of rapidly dropping prices. In less than four years, you probably won't be able to buy a laptop with a rotating hard drive, and "hard drives" will quickly become quaint relics. In fact, within five to seven years, we probably won't even have hard drives on most (but not all) desktop machines.
From an environmental perspective, computing is rapidly moving from being big wasters of energy (CRTs and disk drives use a lot of energy even when the computer is otherwise idle) to being relatively green; the combination of low power LCD flat panel screens and solid state memory will cause dramatic drops in the energy footprint of computers.