Update: moderncv loads the package hyperref by itself with its own hypersetup. From moderncv.cls,

Hence, you need not load hyperref again. But load the hypersetup using \AfterPreamble (or \AtBeginDocument) hook as in this code:
\documentclass[11pt,a4paper]{moderncv}
\moderncvtheme[green]{classic}
\usepackage[scale=0.8]{geometry}
\AtBeginDocument{\recomputelengths}
\firstname{Rob}
\familyname{Ward}
\mobile{mobile +64 21 0377 936}
\phone{phone +64 6 212 0549}
\email{contact@robward.co.nz}
\homepage{www.robward.co.nz}
\AfterPreamble{\hypersetup{
pdfauthor={Rob Ward},
pdftitle={CV for Rob Ward},
pdfsubject={Detailed CV for Rob},
urlcolor=blue,
}}
\begin{document}
% EDUCATION
\section{Education}
\cventry{2006--2011}{PhD physics/biophysics}{Massey University}{Palmerston
North}{New Zealand}{} % arguments 3 to 6 can be left empty
\cventry{1999--2004}{BSc (hons.) physics}{Victoria
University}{Wellington}{New Zealand}{}
\cventry{1999--2002}{BSc mathematics}{Victoria University}{Wellington}{New
Zealand}{}
\cventry{1988--1989}{NCEE}{Central Institute of Technology}{Wellington}{New
Zealand}{}
\end{document}
The pdf properties will then look like:

Earlier attempt:
\PassOptionsToPackage{pdftex,
pdfauthor={Rob Ward},
pdftitle={CV for Rob Ward},
pdfsubject={Detailed CV for Rob},
urlcolor={blue}}{hyperref}
\documentclass[11pt,a4paper]{moderncv}
\moderncvtheme[green]{classic}
\usepackage[scale=0.8]{geometry}
\AtBeginDocument{\recomputelengths}
\firstname{Rob}
\familyname{Ward}
\mobile{mobile +64 21 0377 936}
\phone{phone +64 6 212 0549}
\email{contact@robward.co.nz}
\homepage{www.robward.co.nz}
%\usepackage[pdftex,
% pdfauthor={Rob Ward},
% pdftitle={CV for Rob Ward},
% pdfsubject={Detailed CV for Rob},
% urlcolor={blue}]{hyperref}
\begin{document}
% EDUCATION
\section{Education}
\cventry{2006--2011}{PhD physics/biophysics}{Massey University}{Palmerston North}{New Zealand}{} % arguments 3 to 6 can be left empty
\cventry{1999--2004}{BSc (hons.) physics}{Victoria University}{Wellington}{New Zealand}{}
\cventry{1999--2002}{BSc mathematics}{Victoria University}{Wellington}{New Zealand}{}
\cventry{1988--1989}{NCEE}{Central Institute of Technology}{Wellington}{New Zealand}{}
\end{document}

Note: Noting the comments of Heiko Oberdiek,
Package hyperref does a lot of redefinitions in order to support
non-ASCII stuff in strings for bookmarks and entries in the
information dictionary of PDF files. Much of this support gets lost,
if LaTeX expands the options the hard way before hyperref has a chance
to see them. Therefore it is better to set the information entries
after hyperref is loaded.
this is not always advisable. In this case, it won't give desired results as the hypersetup is over-written later by the moderncv itself.
hyperrefdoes a lot of redefinitions in order to support non-ASCII stuff in strings for bookmarks and entries in the information dictionary of PDF files. Much of this support gets lost, if LaTeX expands the options the hard way beforehyperrefhas a chance to see them. Therefore it is better to set the information entries afterhyperrefis loaded. – Heiko Oberdiek Oct 28 '12 at 12:09attachfile. It loadshyperrefas well which raises the clash error when trying to use\hypersetup. Easy solution for that style: first loadhyperref, then loadattachfile. – Twonky Jul 05 '16 at 09:51