Notebooks are driven by consumers, not business, meaning style will rule in 2009, writes David Flynn.

Slim, svelte and weighing little over one kilogram - that's the shape of laptops to come. Next year looks set to be the year of "thin and light" notebooks. It's welcome news for anyone who has ever cast an envious eye over Apple's MacBook Air.

The stylish and super-slim Air set the pace and already we've seen similar sylphs from leading players Dell, HP, Toshiba and Lenovo. Maybe not quite as Twiggy-thin but packed with features that Apple ignored such as a CD-DVD drive, memory-card readers and more than a solitary USB port. That's a lot of innovation in the 12 months since the MacBook Air made its debut.

But 2009, say the boffins, is the year these "geek chic" laptops move into the affordable mainstream. They'll be lighter and better looking without cutting corners in either performance or battery life.

The general manager of Intel's mobile platforms group, Mooly Eden, says: "Thin and light, or thin and sexy as I prefer to think of it, will be the next revolution." And he should know. As head of the team that developed Intel's Centrino notebook technology, which spurred the worldwide laptop boom following its debut in March 2003, the animated Israeli engineer and self-confessed "chip-head" is considered the godfather of modern mobile computing.

The evolution of Centrino led to last year's development of a chip that is half the size of a postage stamp yet draws less power than conventional, larger processors. It is this tiny slice of silicon, designed specifically by Intel at the behest of Apple chief Steve Jobs, that makes the MacBook Air possible. Now the technology has been further refined and released to every laptop manufacturer.

But while Eden can shape the silicon that powers our next-gen notebooks, he can also hit the wall of their physical limitations. One of these is the fact that notebooks tend to get hot. The thinner the laptop the less space there is for heat to dissipate - even with a small fan to push warm air out through tiny vents in the side of the notebook's chassis. Much of the heat ends up leaking to the bottom of the notebook.

"People used to call it a laptop because they used to put it on their lap," Eden says. "But when you put a thin laptop on your lap it gets very hot. So you have to keep what we call the skin temperature very cool."

Intel's solution mimics the way jet aircrafts work. The inside of a jet engine can reach 1000 degrees but heat can't leak through the engine wall as it would ignite the fuel stored in the wing.

In the same way that cold air from the atmosphere is routed through the engine and its walls to whisk away heat, Intel has developed a way to force layers of airflow between the notebook's circuitry and the inside of the case.

"In a traditional notebook the air from the bottom goes straight up to cool the circuitry but the bottom, the skin, is still very hot," Eden says. "We're just changing the airflow. It still takes the heat out but at the same time it makes the notebook's outer skin between three degrees and eight degrees cooler, depending on the system."

Intel is sharing the design with laptop makers to implement in their 2009 series of Centrino laptops. This new wave of laptops will also be more likely to use solid state or "flash memory" drives rather than spinning mechanical hard drives, a move that also makes for thinner notebooks as well as cooler and longer-running ones. And of course, the chips keep getting smaller, smarter and more power-efficient.

Driving all this is the dominance of notebooks. This year marks the first time laptops have outsold desktop PCs, and the trend is tipped to continue until laptops hold two-thirds of the market. That push is being driven by consumers rather than businesses. Eden says this shift marked "the first revolution" for mobile computing, in which style started to make a difference. "When the notebook went to consumers it was not only about how good it was but about how good it looked," he says.

And when you carry your computer around it begins to reflect your own sense of style and taste. This is what has led laptop makers to embrace colours and curves and use design to make their products stand out. And it's why, in the notebook world of 2009, thin will be in.