I propose to include the Graphviz extension  of Victor as part of mediawiki
starting with 1.5
You could have a first look to the gallery page with plenty of examples and dot
source codes and the manual .
I hereby also ask the developers' community to consider the implementation in
 Proposed for all Wikipedias
 http://www.graphviz.org/Documentation/dotguide.pdf a concise manual for starters