I spent some time to understand how border-image works in CSS3. It does take a bit of visualization to wrap your head around it. On top of that, they really look different in different browsers depend on the browsers’ rendering engine. This is the best tutorial I found on this topic.
I came up with three borders in the new theme I’m working on for wordpress. You can take a look and see whether your browser supports it. (Or you can run your browser against the CSS3 test.)