Windows Developer Preview with developer tools English has been made available for download for developers.
The Windows 8 Developer Preview has been made available now at http://msdn.microsoft.com/en-us/windows/home/
Windows Developer Preview with developer tools English, 64-bit (x64)package includes a disc image which have 64-bit Windows Developer Preview, Windows SDK for Metro style apps, Microsoft Visual Studio 11 Express for Windows Developer Preview, Microsoft Expression Blend 5 Developer Preview and 28 Metro style apps including the BUILD Conference app.
Other two versions also available at the official link provided above where you can download the full image of the disc.
You can watch the keynote right here at http://www.buildwindows.com/. Enjoy making apps