Oh, in case anyone is wondering, the wishlist so far is:

Additional query groups for testing newsletters.

Ability to import/export subscribers (so if you want to use zen for subscriptions, but want to use a more flexible newsletter program to actually send them).

Adjust unsubscribe so it will prefill email field when email is sent (user still has to confirm).

Fix the newsletter script itself (occassionally errors out sending large groups) or at least note what emails were sent so manual fixes can avoid duplication.

Add cc to admin email + config. maybe a 'new' list on index page or manager page.