I made an article about this for the german Macworld Magazine (Macwelt) in 2008 and have found the following applications:
Intaglio from Purgatory Design, Mac, RGB, CMYK Export
Draw Well fom Onestep Solutions, Mac, RGB, CMYK Export
Photoline from Computerinsel, Mac/Windows, RGB, CMYK Export
Inkscape, Linux/Mac/Windows, RGB
Lineform from Freeverse, Mac, RGB
Doodle CAD from Doodle Bytes, Mac, RGB
Zeusdraw from Chromatic Bytes, Mac, RGB (CMYK support added?)
Sketsa SVG Editor from Kiyut Software, Mac/Windows, RGB
Eazy Draw from Dekorra Optics, Mac, RGB
Illustrator von Adobe, Mac/Windows, RGB CMYK
ACD Canvas, Windows, RGB CMYK
Xara Xtreme, Windows/Linux, RGB (Supposed CMYK)
Corel Draw, Windows, RGB (Supposed CMYK)