The required export options settings (for the "Grouping ..." section) are to have only "Object Groups" selected.

Maintaining the correct naming requires a small tweak to the export script (to stop it decorating the mesh name).

Haven't checked recently, but the OBJ importer used to reorder the vertices (which is a problem for morph making), but it can be fixed by using either a Python script (for Poser or standalone -> http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2704761) or a utility from the FreeStuff ("Morpher" by kawecki).