Minimum terms per content-type/taxonomy combination

Issue Summary

Drupals built-in taxonomy module features a 'required' option for a taxonomy applied across all content types for which that given taxonomy is enabled where at one term from that taxonomy should be tagged to the node, a useful feature but not particularly flexible.

A feature in this module (or a sister module) to set a minimum number of taxonomy terms for a content-type/taxonomy combination would be a very useful feature on collaborative/community sites where tags play an important role in classifying nodes, so the site owner can be sure all content has a reasonable nomenclature and depth of expression.

Your thoughts or pointers to similar modules would be gratefully received.