Sequence diagrams (swimlane) for documentation

OpenStack is composed of many services and components. Documenting in both the wiki and sphinx documents includes hand generated graphics of sequence diagrams to show how these relate is currently generated by hand:
http://wiki.openstack.org/ZonesOauth?action=AttachFile&do=get&target=AddChildZone.gif

Updating of those graphics is complicated, perhaps we should use a tool like http://sdedit.sourceforge.net/ which allows us to share our sequence diagrams as text files http://wiki.openstack.org/AuthnAuthz?action=AttachFile&do=get&target=osauth.sdx
which is rendered to images http://wiki.openstack.org/AuthnAuthz?action=AttachFile&do=view&target=osauth.png as part of sphinx build processes?

We currently do something similar with graphviz/dot generating images during a sphinx-build.