From my deep knowledge of all things xaml (insert sarcasm smiley): When you create a style.xaml file that contains the style for DataEnteryTextBlockForeColorBrush. you can reference it via the app.xaml (Silverlight) and it becomes a static resource available to all views. You can also create the style in the view's xaml as a resource (grid.resource/usercontrol.resouce etc) and it becomes a static resource usable by that view only.
Hang on you answer more of these than I do!
Never underestimate the power of human stupidity