I’ve just been building up a new server with CentOS 6.4 and noticed that cpan2rpm wouldn’t work for some Perl modules. The error you get is as follows.

Metadata retrieval
Can't locate object method "interpolate" via package "Pod::Text" at
/usr/bin/cpan2rpm line 522.

Turns out it’s because Pod::Text changed between the version that comes with CentOS 5 (2.21) and the version with CentOS 6 (3.13) and the interpolate method disappeared.

I found a patch attached to this ticket and when applied to cpan2rpm, it works once more. https://rt.cpan.org/Public/Bug/Display.html?id=27309#txn-323456