"new chipsets, new hardware, a new user interface, and a new application model."
Some of the highlighted features include:
Run natively on system-on-a-chip (SoC) designs, including ARM-based processors.
The importance of this development is hard to overstate. Windows on ARM means that Windows devices will get online faster and stay online longer. They can take on new form factors, including tablets and hardware that has yet to be invented.
Deliver touch-first experiences, while supporting legacy peripherals and devices.
Windows 7 “supported” touch but was not “touch-first,” a distinction apparent to anyone observing the use of a Windows 7 tablet or an HP TouchSmart PC. Windows 8 works with keyboards and mice but is truly touch-first, with a redesigned start screen (no more “start” menu!) and a tile-based UI similar to Windows Phone 7.
Build a new app ecosystem, while supporting older desktop applications too.
Windows 8 will introduce an entirely new model for application development and distribution. Apps shown in the tiles will be “alive,” constantly updated and responding to a user’s state. Microsoft will give developers new tools to take advantage of hardware acceleration and sensors, and appears to be launching a store to distribute those apps (more details are sure to come at the BUILD developers conference in September).
Windows 8 has all the earmarks of "post-PC market"; that is, the tablet/portable PC market that includes such devices as the iPad. It'll probably improve gaming, too, as it will be fully DX11 native and designed to be used in concert more fully with the next generation of Xbox.