We went through MDW on Dec 27th. There was a scanner, but it did not appear to be in use.
We always get to the airport 2 hours prior to flight time these days. It seems to be more than enough.
BTW, if you get to MDW early and are looking for food, the best sandwiches (in our opinion) is Potbelly's, just inside security. They have great breakfast sandwiches as well. They are a popular sandwich place around Chicago and the airport location is just as good as the other ones. Their prices are also reasonable!