<p>This may be a no-brainer for the WPF cognoscenti, but I'd like to know if there's a simple way to put text on the WPF ProgressBar. To me, an empty progress bar looks naked. That's screen real estate that could carry a message about <strong>what</strong> is in progress, or even just add numbers to the representation. Now, WPF is all about containers and extensions and I'm slowly wrapping my mind around that, but since I don't see a "Text" or "Content" property, I'm thinking I'm going to have to add something to the container that is my progress bar. Is there a technique or two out there that is more natural than my original WinForms impulses will be? What's the best, most WPF-natural way to add text to that progress bar?</p>

If you are needing to have a reusable method for adding text, you can create a new Style/ControlTemplate that has an additional TextBlock to display the text.  You can hijack the TextSearch.Text attached property to set the text on a progress bar.
If it doesn't need to be reusable, simply put the progress bar in a Grid and add a TextBlock to the grid.  Since WPF can compose elements together, this will work nicely.
If you want, you can create a UserControl that exposes the ProgressBar and TextBlock as public properties, so it would be less work than creating a custom ControlTemplate.