I have seen three:

Dartmouth--more geriatric side of the inpatient general psych-unit.

University of Iowa--Large (around 20 beds) with very sick patients staffed by med-psych, psych, and Internal Medicine Residents.

University of Mississippi--similar to Iowa with 18 bed, staffed by psych resident and double boarded psych attendings.

The key to the med-psych unit is Nursing, finding a nurse who likes (and is skilled in) both floor and psych nursing is hard