Download the Windows 8 Consumer Preview. You may also visit the Windows Developer Center and learn how to sell your apps via the Windows Store.

Whether you are testing, designing, or developing on Windows 8, Microsoft has a support forum for you. New and expanded forums for Windows 8 and Internet Explorer 10 are now available on Microsoft Answers, TechNet, and MSDN. Forum topics include setup, compatibility, performance—even apps.

Visit Microsoft Answers, TechNet, or MSDN to ask and answer questions about the Windows 8 Consumer Preview.
Microsoft Answers Windows 8 Consumer Forum 
TechNet Windows 8 Forum for IT Professionals 
MSDN Windows Developer Center