It is designed specifically around the SVG standard, using the file format (with some extensions to hold meta-information) as its native storage format. It will import and export plain SVG data, and can also export bitmap images in PNG format.
The main author is Lauris Kaplinski, and several other people have contributed to the project.
It is currently at version 0.33. It is quite usable for basic illustration tasks, and in many ways superior to XFig both in terms of functionality and user interface, but lacks documentation.