I agree that system portability is not an issue addressed by CORBA.
But it may address that as well? right..?After all, if we are looking
for truly distributed software systems, we should have mechanism to
develop such system as welll uniformly?

So my version is it should not take much for OMG to extend its
specification to cover abstraction over underlying os as well, as it
affects distribution, deployment etc.

My view is mapping may not be standardaized suppose. but the names of
stubs/skeleton files can be standardized so that we dont have to change
the name everytime we change ORB at least? And anyway it doesnt affects
any other behaviour right? Just a name change.

I could not get how it provide vendors more flexibility by not
standardizing the header file name? what flexibility u r referring to?

Its true most of the ORB provides mechanism to specify the header file
name, but that is an unnecessary step.