Microsoft have announced that the first beta exam for Windows 8 is available starting in June 2012. The first Windows 8 exam is 70-687 - Configuring Windows 8. It forms the foundation for the new MCSA and MCSE certifications.
The final version of the 70-687 Windows 8 exam (not beta) should be ready on September 17, 2012.
Even though the exam will be in beta until September, you can still register for the exam and pass it as if it were the real thing. It will still count towards the final certification for Windows 8.
However, Beta exams are test versions that Microsoft experiment with to make sure they get the test questions right for the final version. Beta's can contain incorrect answers or mistakes, or subjects outside the scope of the exam. By taking a beta exam you agree to these risks and also the uncertainty about testing against an unreleased software product.
Since this is part of the MCSA certification route, the exam focuses on installing, upgrading and configuring all aspects of Windows 8. You'll need to be comfortable answering questions about devices, hardware, Hyper-V, networking, security and access, updates, backups and recovery.