Liquids are much better than air at transferring heat from one place to another, like from a busy CPU or GPU to anywhere else convenient. This is why if you're trying to air-cool your PC, you need either a bunch of big fans, or you can use a compact liquid cooling system. It seems a little weird, then, that it's taken this long for someone to cram liquid cooling into a laptop.
Asetek has kludged together a prototype liquid cooling system for an Alienware M18x gaming laptop, one of those gaming rigs that seems likely to crush and/or burn any lap that it's used on. Inside is an Intel Core i7 running at 3.5 Ghz, along with dual AMD Radeon HD 6990M graphics cards. Most laptops with specs like this use two or three separate cooling systems, with a fan and a heat sink for each CPU and CPU. That's not a particularly efficient way to go, since besides having multiple systems to deal with, it means that if you're just using the GPU(s) and not the CPU (or vice versa) you'll be wasting a lot of cooling potential.
The solution that Asetek came up with is to create one liquid cooling system that circulates through every part of the laptop that needs active cooling. This is much more space-efficient and cools significantly more effectively than discrete heat pipes and fans, even to the point where the laptop can be overclocked without turning into a melted puddle of plastic and silicon. Benchmarking showed performance increases ranging from 18% to 23% across the board, while the laptop's cooling fans were able to run slower and quieter.
Even though this system is relatively compact, it looks like it's probably only going to fit in the beefiest of laptops, which are likely to benefit the most from improved cooling anyway. Still in the prototype stage, there's no word from Asetek quite yet as to when we might see commercial availability (or the option for a retrofit).