Very soon you will be able to do so! On May 6, Microsoft will be launching Technical Specialist exam 70-571 (Microsoft Windows Embedded CE 6.0 Application Development) at Prometric Testing centers throughout the US (the exam will be rolled out internationally on May 21).
For details on how you can receive a 50% discount on the cost of the exam, please visit the Microsoft Certification for Windows Embedded CE 6.0 on MSDN.