I am in the process of designing a .net windows forms application that uses metadata to drive the UI. Apart from finding http://msdn.microsoft.com/en-us/library/ms954610.aspx, I
You may try this with HTA. Sometime back I created a metadata driven application using HTA and XML. I created XAML like structure and HTA-VBScript code to parse this structure and render diffent types of UI elements along with validations.
You may want to check out Evolutility CRUD framework. It is an open source metadata driven framework for CRUD generating all UI at run-time.
It comes w/ source code (in C# and JS) and many samples.
http://www.evolutility.org
Check the Andromeda project out, which does so extensively. Too bad the stack isn´t .NET friendly (PHP, Postgres, Perl).
The most obvious answer would be that Microsoft have themselves embraced this concept through their use of Xaml in Windows Presentation Foundation which replaces WinForms (to an extent).
If you want to stick to a WinForms, you may want to consider MyXaml which is kind of a homage to Xaml for WinForms!