"The fact that Microsoft has adopted XAML really is a validation that XUL was the right direction to go. Once again MS takes what is out there, changes it slightly to make it it's own, and then grafts it into Windows in a proprietary way. This behavior pattern is predicatable as clockwork for MS."

"Microsoft has no monopoly on Longhorn features. For example Avalon's vector rendering engine is neither unique nor even innovative. Technologies like Flash, Shockwave, PDF, and PostScript all use vector engines today. In fact, all platforms already perform vector processing for restricted tasks such as rendering modern fonts. XAML isn't a new idea either. Announcements of XML interfaces for various technologies have already begun, and are only likely to increase."