conn-aliasing.c polls for nicknames using PEP in some situations. Since we cache contacts' nicknames on our roster, it's not *such* a big deal, but we probably shouldn't do this.
Historically, ejabberd has not pushed nodes' initial states to us when we have +notify in our caps (see also bug 27693). There's a big FIXME in the code about this. We should try to get this resolved on the pubsub list. All other implementations seem to do the right thing, so we could just declare ejabberd to be broken.