No, this is just the stock perl in Ubuntu. I'm calling cpan using the simple shell front-end that it installs. And you're correct that /usr/share/perl/5.8 is a symlink to /usr/share/perl/5.8.8.

The last set of modules I'd installed in the run prior to this were AnyEvent, Config::Any, Module::CPANTS::Analyse, Module::ScanDeps and Safe. I think I'll try to roll back the Module::ScanDeps change, since that's the only one I can think of that would interfere with CPAN.