[Implementations] EPiServer CMS

"EPiServer CMS - the world's fastest growing commercial CMS platform - is  
a fast, flexible and robust Web Content Management system."

Uses XForms, and apparently has a WYSIWYG forms designer.

Developing with XForms
http://world.episerver.com/en/Documentation/Items/Tech-Notes/EPiServer-CMS-5/EPiServer-CMS-5-R2-SP1/Developing-with-XForms/

Blog using XForms in EPiServer
http://blog.najmanowicz.com/2009/03/17/get-out-of-my-way-or-the-story-of-file-metadata-for-virtualpathprovider-in-episerver/

Steven