Shop hops are when a group of shops get together and advertise to come visit their shops over a set amount of days. They usually offer a freebie, pattern or some other specials during that time. It affords them the increased foot traffic, and for the visitor an incentive to come shop their store again. It's like a quilting open house.
I've been on a few and have enjoyed them (except for the last one I was on). I go alone so I can do my own pace even tho' it would be fun to have someone along to share ideas.
If you get the opportunity, GO!!! And have fun!