Please, do not use non-standard documents!  You can get a copy
of the Final Committee Draft of the Fortran 2003 standard from
the J3 web site (or you can ask me to send you a copy).  Vendors
tend to interpret the standard in a manner that suits their needs.

BTW, this feature is actively being worked upon.  See
http://gcc.gnu.org/ml/fortran/2005-12/msg00270.html

Confirmed

Seems this work is getting closer: http://gcc.gnu.org/ml/fortran/2006-04/msg00173.html

I'm adding this bug as blocking 27740, as before taking symbol versioning into use, it would be nice to clean up the library interface; in particular making all exported symbols have the _gfortran_ prefix. As the Fortran language doesn't allow procedure names to begin with an underscore, and parts of libgfortran are written in Fortran, the C binding could rescue us here as we could do

function foo(a,b,c) bind(c,name='_gfortran_foo')

This feature is now part of the "fortran-experiments" branch, available at:
svn://gcc.gnu.org/svn/gcc/branches/fortran-experiments

I committed a patch, yesterday.