Look, up in the sky, it's a gui, it's a browser, its WPF/E (WpFe) ...
No, just little ol' me, XaMl.
An important part of XaMl is XPS, the PDF killer. Its design principles according to blogger Andy Simonds are: Open Format, Trustworthy, High Fidelity Graphics, Platform for Innovation, Integrated Solution.
Note MicrosoftOffice version 12 will stored files natively as OpenXml format, and have "export" to XPS and other formats.