The microperl implementation in the gumstix buildroot has a few issues that prevent it from being really useful:
  %ENV environment support is missing
   System call support is somewhat buggy when using redirection, pipes, and quoted parameters
   Symbol export from packages is not supported

I've made modifications to my buildroot to resolve these issues.  The patch files are a bit too big to post on the list, but I would be happy to provide them to anyone who might need them.

Caveat:  Use at your own risk -- they seem to work quite well in my application, but I haven't run extensive tests.  The two patch files originally came from the openwrt site I referenced in an earlier post on this topic.  I've modified them slightly  for gumstix.

The changes are localized to 3 files in the package/microperl directory: a revision to microperl.mk and the addition of 2 patch files. 

microperl.mk has been changed to apply the 2 patches before building microperl and also to copy a small number of modules to /usr/lib/perl on the target system ( strict.pm, Exporter.pm , Carp.pm, and Exporter/Heavy.pm).  These modules are the minimum set required for module symbol support.

Steve