In case anyone in the same boat is reading this and wondering what happened, the passport just got delivered, and included in the packet was the "your PR has been approved" letter. But we still don't have an email from INZ, so I was very grateful to get that email along with the passport. I mistakenly thought that we had to send the passport off because they were going to put a stick in it, so the fact it was en route back to us without an email approval was making me nervous.
Anyway, it's been about 5 weeks since the money was deducted (and that took about a month from posting the application off) all up - not too shabby at all considering how swamped they must be!