If you receive the following error when trying to install a CPAN module using Mac OS X Leopard and Perl 5.8.8:
No rule to make target `/System/Library/Perl/5.8.8/darwin-thread-multi-2level/CORE/config.h', needed by `Makefile'.
..then salvation is at hand.
Mac OS X Leopard Perl
The problem (in most cases) is that files are missing from the 5.8.8 Perl installation and are present in the older 5.8.6 version. To correct the error you simply need to copy the files from the 5.8.6 directory to the 5.8.8 dir. Execute the following command as root or using sudo:
cp /System/Library/Perl/5.8.6/darwin-thread-multi-2level/CORE/* /System/Library/Perl/5.8.8/darwin-thread-multi-2level/CORE/
You should then be able to install Perl modules happily.