Just a heads up for others who might be tempted to use the latest blender exporter that there are some issues! Namely, all the meshes that get generated by the new blender exporter use shared vertices and while these models will appear fine in your applications you may notice that the shared vertex data of the mesh is invalid or non-existent. This is important if you are planning on reading vertex positions to generate collision hulls for example.
I tried converting the models with OgreXMLConverter on OSX & Windows using the old download version, the sdk version, and a build version and all had the same issue. I suspect that there is something OgreXMLConverter doesn't like about the shared geometry in the .xml files the new blender exporter generates.
When I switched to the older Blender 2.4 and the old exporter the .mesh files do have valid vertex data. Wish I had time to debug the issue! It'd probably be evident by stepping through the import of the file in the MeshSerializer code what is going on.