Laura,
I recall reading a piece by Julian Savulescu in 2002 on the future of value argument..
Abortion, Embryo Destruction and the Future of Value Argument JME 28, 133-135.  It is a
short piece that likely does not supply as much argument as you are looking for, but there
may be some helpful references there.
Best,
Kyle
Kyle Anstey
PhD Candidate
Centre for Apllied Philosophy and Public Ethics
Department of Philosophy, The University of Melbourne
Australia 3010
http://www.student.unimelb.edu.au/~kwanstey/