Introduction To XAML
prostoalex writes "It was recently reported that Microsoft will integrate its own XML-based language for application programming into the next edition of Windows (codename Longhorn). This Introduction to XAML (Extensible Application Markup Language) provides an insight into how it's possible to build a Windows application with Microsoft's brand-new XAML language."
The idea of XML-based interface definition has been around well before XAML. There are a ton of XML user interface languages around: http://xul.sourceforge.net/. Hell, Mozilla is built around it: http://www.hevanet.com/acorbin/xul/top.xul