Description of problem:
cpan> install GD fails on F-13 (and earlier I think)
this is because the .so symbolic link is in the -devel package,
not the base package.
I dont understand why the symlink isnt also in the base package,
since programs wanting libgd shouldnt have to ask for a specific
version, unless they actually need that version.
Once I installed gd-devel, cpan install worked as expected.
Unless I am missing something, you are rebuilding some code against GD. So in that case you need the -devel package. The .so is not needed at runtime, so it is not shipped in the base package (and it is the case for all the libraries in fedora).