It was removed from Tiki 4.0 because it was unmaintained, buggy and many of the things can be done with the more recent PluginAnnotation.
The database tables are not removed when users update to 4.0 to preserve any existing data. However, new installs will no longer have them.
If a maintainer volunteers, it could be re-instated with more recent version of jGraph.
A flash-based solution
An Ajax-based solution
An HTML5 based solution (best!)
Please see: Collaborative Image manipulation