We have Three different guides one for consumers, one for Business, and of course developers.
The consumer one:
Welcome to the Windows® 8 Consumer Preview. Windows 8 has been reimagined to focus on your life. The beautiful, fast, and fluid design is perfect for a range of hardware: from compact, touch-enabled slates and lightweight laptops, to large, powerful all-in-ones with high-definition screens. It’s smooth, intuitive, and gives you instant access to your people, apps, and stuff, so you spend less time searching and more time doing.
Download it here:
Product Guide for Consumers (6.43 MB, PDF)
The Business one just got updated:
The Windows 8 Consumer Preview Product Guide for Business provides a detailed look at the many new and improved features in Windows 8. The guide is designed as an accurate source of information that can help businesses understand how Windows 8 enables users to be ready and productive practically anywhere, allows for a personalized user experience, and provides IT with more secure, easy-to-manage intelligent infrastructure.
Download it here:
The Developer one
If you’re a developer, Windows® 8 Consumer Preview gives you an amazing platform to reach the millions of people around the world who use Windows every day to be more productive, creative, and to have fun. With Windows 8 Consumer Preview, you have unprecedented access and opportunity to reach that worldwide customer base early. Windows 8 represents the most significant platform opportunity available to developers, with a chance to reach millions of people with your amazing Metro style apps.
Apps are at the center of the Windows 8 experience. They’re alive with activity and vibrant content. Users are immersed in your full-screen, Metro style apps, where they can focus on their content, rather than on the operating system.
Signing up to sell your app in the Windows Store means you can tap into the worldwide user base of Windows, even at the Consumer Preview stage. You’ll draw from a wealth of new tools and services, including updated versions of Microsoft® Visual Studio® Express, Microsoft® Expression Blend®, an optimized Windows 8 SDK, and personalized app telemetry data, so you can develop and deploy apps faster and more proﬁtably.
With Windows 8, you can leverage your existing skills and code assets to create Metro style apps for your customers.
With Windows 8, you’re ready to imagine, build, and sell the next great app to the entire world.
I am frustrated that there doesn't seem to be any forum where I can discuss shortcomings, bugs and confusions with the preview of Windows 8.
Try http://answers.microsoft.com for support