Well, thanks to the recent arrival of the texture canvas resource and some pointers from the staff concerning shaders, I recently started a mesh implementation. Building on this, as of last night I have some Spine meshes rendering, using a few assets kindly provided by sirmania: link
It's still a bit lacking: there are no per-vertex colors (I'm not sure I have anything to test this with, at the moment) nor FFD (I believe I've got a mesh that uses this). Also, the draw order needs fixing somewhere. Otherwise, you might be good to go. (The mesh stuff is implemented in mesh.lua and the impl directory. It's a bit messy and not well-commented or -documented!)
These aren't straight-up display objects, so various properties like rotation, scaling, and so on probably won't work quite as expected, if these are even relevant. Perhaps as I refine the mesh object I could address some of them, or maybe something official will land down the road.
I've made a pull request of the non-Corona-specific bits to the Spine crew, so possibly that will make it in soon. We'll see what they want to do about the rest.
I think I'll leave it a few days before giving FFD a go. In the meantime, let me know of any weird results.
EDIT: Some of that other stuff (more or less) works now too.