There is a plan, and there are two solutions.
1) Using Vizjs http://plantuml.com/vizjs
This solution works fine, however I am not sure how it integrates with Confluence.
You have to go to Confluence team to know more about it
2) A port of GraphViz in Java http://plantuml.com/smetana02
This solution is possible out-of-the box, that is it will work with your current config.
Unfortunately, the port is not complete, so only some features are working.
So I don't know if it will fit your need.
Hope this helps!