I've hacked the code to force a user to login, but being able to simply toggle this would be great. With forced user login turned on, then two features I'd like to see are:

1. Tag pictures with what users are in them (choose from drop-down / checkbox / whatever, etc)
2. Comments are automatically tagged with username (and email, website, etc) instead of having to type it in every time.

The next release of zenphoto will use a dropdown list for specifying tags (in the admin interface). You just need to enter the name once and it will be available there after for assigning to images.

if you include `` in your comment form (all the zenphoto themes do this) then the user will have to enter his information only once.