I don't know how common our situation is... We use VTK through it's Python interface but we also need to develop some algorithms in C++ and make them accessible to the Python runtime. The problem is that, as far as I know, the VTK bindings are not inter-operable with swig. The result is that we can allocate VTK data structures from Python but we can't give them to our C++ algorithm.
There are multiple solutions to this problem. The one we chose is to use swig to wrap our algorithm *and* VTK, in two different but inter-operable modules.
We will start by wrapping and testing the parts of VTK that we need right now, but if other people out there have a similar need perhaps we could collaborate and come up with better bindings.
So... is there anyone interested in participating in this not-yet-born open source project?