We did this last year at our local Wegmans and it was a big hit with my (then) 3 year old! Kids go through the store and trick or treat at different stations. The trick or treating at my local store (Manalapan, NJ) will be on October 29th, Friday night.
This year my store is asking parents to sign their kids up and get tickets in advance - so they know how many kids to expect. We signed up today and were 260 and 261 on the list!!! It does get crowded, so arrive early!