Please post links to screenshots and/or insights of this vector graphics application. We must learn from others.
Karbon14 is the vector drawing application in KDE and part of the KOffice Suite. Being part of a suite is a big advantage and allows Karbon14 to get a foot in the door as it will be included simply because people are interested by some other application in the suite. Other parts of KOffice such as KChart and Kivio have support for SVG Export and there is potential for Karbon14 to intergrate more closely more closely and leverage their functionality. (Adobe Illustrator includes graph and charting functionality.)
Karbon14 (Draw) and Krita (Paint) have started to share infrastructure including gradient loading and both can now make use of SVG gradients and future improvements will benefit both applications. There is much more potential for sharing of work and reuse of code across the suite which has not yet been exploited. Primarily KOffice uses KPart embedding but it seems likely as KOffice completes its move to the OpenDocument standard more and more things can be shared at a more fundamental level. Integration and reuse of features already in KOffice could make a signficant improvement to Karbon14.
Karbon14 used a custom XML file format but is migrating to use the OpenDocument file format standard along with the rest of KOffice. Karbon14 has limited support for importing and exporting SVG.
Karbon14 supercedes older efforts to provide Vector Graphics Editing for KDE including Killustrator and Kontour.
GNU General Public License (GPL). (Parts of KOffice are LGPL to facilitate embedding within other applications but Karbon is not.)