I'm a geekette who enjoys playing with new technology for software developers. I work as a Developer Evangelist for Microsoft. My current focus is on machine learning and big data on Azure.
The Windows 8 Release Preview has been released. You can download it from here. If you are prompted for a product key, use TK8TP-9JN6P-7X7WW-RFFTV-B7QPF. To do Windows 8 Metro development, you will also need to download the Visual Studio 2012 Release Candidate.
Here are the top links that you need to read to get up to speed:
Developers in large enterprise companies may also want to check out how to plan for Windows 8 and the Windows deployment guide.