Housing is provided at the following Maine locations:
EMMC - there are in-hospital dorms. This Spring, a new building across the street from the hospital will be finished and available for student housing. Looks very nice, students will have their own rooms, there will be internet access, etc. This housing is free.
CMMC - there is a student house available first-come, first-served. It is also free. They are nice at CMMC about giving you free meals in the cafeteria while you are doing your rotation. I was pretty shocked, because I didn't get free food anywhere else!
St. Mary's in Lewiston - There is a small student apartment, three bedrooms, also first-come, first-served, and free. No discount in the cafeteria.
Maine Med - There is a house called the "Thomas House" that is used for students, but not really offered for third year rotations. It was offered to me for a 4th year rotation, but i declined since I live in the area. Sometimes, there is not enough room in the house, and students are asked to move out (this is what some UVM students told me). It is free if you get to live in it. Cafeteria food is discounted.
Mercy - I haven't heard of them having any housing. I did one rotation there for 4th year, nobody mentioned housing and i didn't ask because I didn't need it. Discounted food in cafeteria. Parking sucks.
Southern Maine Med - I have no idea about housing here.
Maine general Hospital in Augusta - There is a student house. It is free. I don't know if there is cheap food. This is a relatively new site for core rotations.
Hope this is helpful for people who are interested in Maine, and maybe other will chime in with their housing experiences.