From the Windows Forms site: Windows Forms Markup Language! For the .NET Framework version 1.1 (as in: you can use it today).
I’m in the middle of an in-depth study of ASP.NET 2.0, but this is work a quick aside. Going to download today!
Windows Forms Markup Language (WFML) provides an extensible mechanism to add a markup model on top of an existing .NET Framework object model. WFMLs parsing rules can be summarized as “XML elements map to .NET Framework types and XML attributes map to Type properties (or events)”. This sample includes a WFML parser that dynamically generates an object instance tree from an XML file in WFML format.