As reported over on ExtremeTech, Internet Explorer 9 will support hardware acceleration usnig the GPU within your PC.
The GPGPU engine will work with either AMD or NVIDIA card by offloading rendering operation from the CPU to the GPU. This allows the CPU to deal with other things like Javascript or other processes.
In addition, the IE team is also working on speeding up JavaScript performance by taking advance of dual or quad processors by compiling the code on one core and running it on another
The bad news is that Internet Explorer 9 with all the multi core and GPGPU suport will only work on Vista and 7 and server products from Microsoft. XP users are totally not supported.
If you are running Windows Vista with Service Pack 2 or newer, you can download the platform preview directly from the Test Drive website.