I also started from same code, and made some changes which might be useful to CPAN::Mini. Take a look at: http://svn.rot13.org/~dpavlin/svnweb/index.cgi/perl/log/trunk/mirror_cpan.pl
I thinks that most useful feature is creation of (optinally compressed) readme file for each module. That allows me to use readme command from cpan shell (which I do a lot :-)
Are you interesed in this change so that I can stop maintaning my own version?