Graph layout with Metapost?

Hi List,

I was wondering if anyone had ever tried to implement graph layout
features (like Graphviz, see http://www.graphviz.org) using
Metapost. I really like the graphviz tools but I think the most
annoying deficiencies are:

1. Text layout capabilities are poor. I started working on
   improvements, but Graphviz' support of a gazillion output drivers
   doesn't make things easier.

2. You cannot add anything to the graph

The existing Metapost output driver is not an option for me since it
doesn't solve any of the two problems.

Ideally, there would be add-ons to Metaobj... Denis?

Best regards,
     Marcus