Mason and Template Toolkit basically generate Perl code. HTML::Template, on the other hand, is a pure separation of template from code.
Should you be concerned if the module hasn't been updated in some time? Only if you find yourself worrying when the IPv4 protocol is still in use without any significant changes for some time. Only if you find the cron daemon a bit outdated for your liking.. My point is that if something works and does what it says on the box then stability is generally a good thing.
Updated: grammatical corrections.