Using XAML vector graphics in WPF application

http://learnwpf.com/post/2006/06/04/How-do-I-Include-Vector-Based-Image-Resources-in-my-WPF-Application.aspx explains how to do it.

<ContentControl Template="{StaticResource Credit-Card}" />

It is extremely difficult to use vector graphics in a reusable way in WPF and Silverlight.

These two StackOverflow questions discuss some of the options available:

XAML Icons - How to use?

WPF What is the correct way of using SVG files as icons in WPF

After reading through these questions and answers, I think the best solution is to stick with with a bitmap/raster format like PNG until Microsoft decides to support SVG.