What is it about
Need to decide how to handle copyrighht file generation.
Here's how debian/copyright, the packages license file (there is no meta field for this, it's a file) works:
http://people.ubuntu.com/~cjwatson/ubuntu-policy/policy.html/ch-docs.html#s-copyrightfile
dh_make, a templating command we'll be using (everyone uses it) generates only the files for gpl/lgpl, and not the rest, we'd need to keep a stock file of all the licenses ourselves (and might as well do this for gpl/lpgl too).
Impelementation
Since copyrights will be common to all packages, it makes sense to include this functionality in the core (or maybe as a plugin... however that would sort of remove the purpose of a plugin, multiple plugins would make sense - but there are tons of licenses too).