A campaign was started at IndieGoGo - a european "kickstarter" - to develop a professional PDF creation tool for Inkscape. The plugin's main features include: exporting projects in RGB or CMYK color space, using color profiles; Adding custom bleed area, as well as crop & bleed marks; extensive control over quality and compression. The projects has been started by graphic designers.
You can find more details at: http://www.indiegogo.com/Advanced-PDF-export-plugin-for-Inkscape
I have looked up the project and now waiting for a comment!!!
Wena