This is probably the final update for the Drawing module. I am going to an astronomical camp tomorrow, where I will have hardly any internet access.
Documentation for the Drawing API (without the graphing part, because that is very flexible right now): http://drupal.org/node/161562
What I'm planning to do in my absence is to do some further code cleanup, and to merge the patch sent by schuyler1d to resolve a firefox rendering issue. The module now contains the basic foundation of a graphing API, I will try to extend it.
In the meanwhile if you are interested, check out the latest code from cvs, or check the demo site for examples of usage.
I will give a talk at FrOSCon about the Drawing API on the 25-26th, and I offered to give a session on Drupalcon, Barcelona. If you like the idea, vote on the talk. Feel free to give in your own ideas regarding what this drawing ability of Drupal could be used, I will investigate the request and include it in the talk if it fits.