Hi,
We have added Eigen to VTK as a third party library, and its use has been introduced in a few places. This was a longtime in the making, and I had hoped to get it in much sooner. Over time its use will hopefully be adopted in more places within VTK.
Part of the reason this was even possible for us is the license change, so I want to thank everyone involved again for making that change. I think Ben is working on getting a few patches merged to address issues found since adding it.
I am very much looking forward to being able to use Eigen in VTK development.
Yours sincerely,
Marcus