Thanks Florian, I figured out the chain of depends and recommends which resulted in zeroconf getting installed. It came from installing rhythmbox, then
rhythmbox Recommends: scrollkeeper, yelp, avahi-daemon avahi-daemon Recommends: libnss-mdns libnss-mdns Recommends: zeroconf I would that think that rhythmbox should only suggest avahi-daemon? But I that has already been discussed on debian-security (http://www.mail-archive.com/debian-security@lists.debian.org/msg32391.html) and I guess this is just the way it goes.
