I'm interested in this as well. I tried using the Blender .ply importer and various Python .3ds loaders to load data into (a development version of)
my library--it's not specific to my library though--I just need things like arrays of vertices, normals, etc. to pass to my object class. So far, I've not had much success, but if anyone wants to make .ply and .3ds loaders, I'd like to help.
My present solution to loading such files is to use Blender to convert them into .obj files, which I can load using a (heavily modified and upgraded) version of the cookbook recipe. Ideally though, I'd like to support new file formats (particularly .ply and .3ds).
Ian