We're Out!
Woohoo! The fisrt Community Technical Preview (CTP) of Indigo is now available for download at https://msdn.microsoft.com/longhorn/ (currently restricted to MSDN subscribers, but will open up to all soon).
The documentation and samples for Indigo are part of the WinFX SDK. The SDK is available through the CTP package, and also available online at https://winfx.msdn.microsoft.com.
Have fun!