Can a Vertex Group be saved as a separate .blend File? I've created a model using makehuman after editing the hair mesh and recoloring the texture I would like to save this part of the model to be able to reuse it with other models. 

Can a part of a mesh (including an armature and material) be saved in another .blend file for importing later?

I tried to select the hair mesh and invert selection to delete everything else, but there are way too many items in the outline view.

EDIT:

The effect after Ctrl, delete all, C Ctrl-V is the same as when append or link will be used to load the hair mesh, unwanted custom shapes and other stuff comes into the new scene.

Append .blend/Mesh/test_clothHairLongMesh2 has no effect at all and append .blend/Object/test_clothHairLongMesh2 loads all the stuff described above.
The best way I can think of is, for safety duplicate
the original object first as you suggested,
then remove the other parts of the mesh:


Select the part of the mesh to keep.
Press CTRL + I to Invert Selection.
Press X and Vertices to delete excess parts.




Or (not so good solution) you go back to object mode,
select the object if it is not already the only selection,
and export (for example as collada), and check only selected.
Later you can import the exported mesh.

Or you may give a nice name, like APPEND-WITH-ME, and you can
simply append your other blend file and select that object
(not the mesh, the object). Every material, particles,
etc will be also loaded into the new blend file.