Or you can pull in some packages only (perl, in this case) from newer Debian versions.

Notes:

• Using aptitude rather than the plain apt-get shown in the link above seems like a better idea (improved dependencies, conflicts, etc. handling).
• While I often use this trick on computers I manage, I've never tried it for perl. It's possible that it depends on too many packages to work correctly (ie. depends on half of testing, in which case you may as well upgrade completely).

Not directly relevant to your question, but if you stick to a Debian perl, you can also use the excellent dh-make-perl tool. It allows to build Debian packages directly from the CPAN. They integrate well with the system and can be managed using standard tools (dpkg, apt-get, aptitude, ...):

dh-make-perl --build --cpan Some::Module \
  && sudo dpkg -i libsome-module-perl*.deb
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