This sounds like it would make life a lot easier for automation. I hacked together a build system a few weeks which used CPAN.pm to install modules which were specified in an xml file that had module name, author, and version. I hit several roadblocks when working with Module::Build based modules because I needed to use PREFIX functionality.
I ended up having my build system bootstrap a fresh perl installation, source a new profile, install a CPAN Config.pm, then prompt the user to re-run the build under the newly installed perl. It solved several problems with regards to the Module::Build issues, but had the downside of taking a long time to setup from scratch. On the plus side, to upgrade to a new module, all I had to do was update the version in the xml file, and run 'build --module module_name'. No modules to download and add to the source repository.
in reply to Module::Build users -- please use the "traditional" create_makefile_pl option
Here's a snippet of the build config file:
<module name="Apache2::AuthCookie" path="M/MS/MSCHOUT/" version="3
<module name="CGI" path="L/LD/LDS/" version="3.08"/>
<module name="BerkeleyDB" path="P/PM/PMQS/" version="0.26"/>