Thanks for pointing that out ikegami, I wasn't aware that Perl 5.10 had been end-of-lifed.
The reason I was thinking of Perl 5.10 was because that's the version that the latest Ubuntu LTS (10.4/Lucid) supports. Upgrading to a non-LTS version of Ubuntu means you only get support for a year and then have to upgrade again.
Installing a local version of Perl separate from the Ubuntu repos is possible but not ideal.