Ubuntu 12.10+ (includes GIMP 2.8+)
Hint: in Ubuntu Software Centre, search for 'inkscape' and install
Advanced (3D Graphics): Blender 2.64+
Layout and eBook: Scribus 1.4+
Gimp: gimp.org/docs/, gimpmagazine.org/resources/
Inkscape: inkscapeforum.com/viewtopic.php?f=11&t=2, inkscape.org/doc/
Blender: blender.org/education-help/
Scribus: wiki.scribus.net/canvas/Scribus_Links