Microsoft has launched a developer preview of Microsoft Windows 8 to the general public. The location can be found here:

Windows Metro Style Apps Developer Downloads

The information contains an assortment of details about the operating system, including the core OS itself, as well as the Metro UI. While unofficial leaks have spurred rumors and nonsense, an official preview release from Microsoft is sure to provide solid information and a foundry for developers to begin programming Windows 8-based applications. Even those that would run under Windows 7.

The Windows Developer Preview is a pre-beta version of Windows 8 for developers. These downloads include prerelease software that may change without notice. The software is provided as is, and you bear the risk of using it. It may not be stable, operate correctly or work the way the final version of the software will. It should not be used in a production environment. The features and functionality in the prerelease software may not appear in the final version. Some product features and functionality may require advanced or additional hardware, or installation of other software.
Over the next few hours and days, we will be providing a massive amount of information on this release: As much as possible to show off what may appear to be new features and functionality.