Unfortunately, the original creator of this project is no longer able to maintain it.
As such, I am hoping that people will come along with an interest and the time to pick up the project and keep it alive. ZedGraph is well-written and documented, and it would be a shame to let it fall apart.
I have complete admin rights over the project, but not the time or C# experience right now to commit to it.
The domain, zedgraph.org, has been renewed for another two years, so this site isn't going anywhere.