User documentation is now available in the new website http://doc.orbisgis.org.

Documentation for developper is available on the OrbisGIS's Trac here : http://trac.orbisgis.org.

Have a look in the “documentation” part in the wiki menu. You will find informations about GDMS, how to develop plugins, …

In the Trac, you will also find OrbisGIS source code, the timeline and tickets (bugs and requests).

If you have some problems or you have some specific questions with OrbisGIS, don't hesitate, post in the new mailing list (click on the picture below)