Version: (using KDE Devel) Installed from: Compiled sources Umbrello should come with some example files. This will help both press people wanting to make screenshots, and also users who need to see what the app is capable of.
Have you looked at http://uml.sourceforge.net/screen.php (screenshots) and http://uml.sourceforge.net/developers.php (xmi files) ?
I've asked for an Umbrello section on the soon to be released kde-files.org, then we can have a Get Hot New Stuff feed and you can download the latest and greatest Umbrello examples.
There are now some example and test files available. More will come.