"Extensible Application Markup Language (XAML) is a declarative XML-based language created by Microsoft which is used to initialize structured values and objects. XAML is used extensively in .NET Framework 3.0 & .NET Framework 4.0 technologies, particularly Windows Presentation Foundation (WPF)." *

RC-WinTrans can be used to translate XAML files and the GUI objects can be rendered/modified with the WPF GUI Editor Add-On.

* Wikipedia entry: