I'm just getting my feet wet with WPF and XAML and wanted to see loose xaml work. The simplest example I could find:

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
<TextBlock>Hello World!</TextBlock>

will not load in either ie8 or firefox 3.5. In ie8 it result in ye olde "Internet Explorer cannot display the webpage" error. I have loose xaml enabled in the security settings for each zone.

What am missing?