From the roadmap overview:
(http://www.inkscape.org/roadmap.php)
6. Create Plugin Architecture 0.40 * This architectural change will establish a new mechanism for how features are added and maintained in the codebase. 7. New Features 0.41 * Implement snap-to object, enhanced layer support, and boolean operations. 8. STL Architectural Change 0.42 * Shift codebase to using STL for data structures. * Replace use of #defines and enums with hashmap lookups 9. Extract SVG Canvas into a library 0.43
Obviously I'm massively ignorant of the issues involved, but from what I can see milestones 6 and 7 are relatively independent of 6 and 9.
From a GO perspective, it would absolutely brilliant if you could bring
milestone 9 into milestone 6, the point at which you might start using libgoffice for the plugin handling. (And I personally hope you do because it will help make goffice more functional, featureful, and robust as well as give Jody a bit of help.)
The reason I bring this up is that the sooner the Inkscape SVG canvas is available, the sooner other applications (esp. GO apps) can organise themselves around incorporating it.