Back in the late 90s Halloween fell on a Sunday and all the local fundies got their over-righteous big girl panties in a wad and started a movement to change Halloween from "their" day to Friday or Saturday.
The city council caved to the pressure and actually deemed that Trick-or-Treat would be officially done on Saturday instead of Sunday. Of course, this only created a lot of confusion, because not everyone keeps up with the proclomations from city hall.
The church-goers praised God for saving his day, the skeptics and Halloween lovers cried foul and Trick-or-Treating ended up happening on both nights. Some followed the proclomations, others didn't know so went out on Sunday and the enterprising kids went out both nights.
This year some people tried to start this crap again and this mayor knew to nip it in the bud and declared that Halloween is October 31st, no matter what day of the week it fell.
I think it's cool to have it on Sunday. A lot of the adults and bars/clubs are having their parties on Saturday night and then Trick-or-Treating and parties for the kids is on Sunday. It becomes a two day holiday...fun for all.