A block of 20 rooms has been reserved for MPIG attendees at the UIC Medical District Marriott. The room rate is $149 (singles and doubles) and includes free internet. The hotel is conveniently located within walking distance to the Saturday progam and very near highways and public transportation (trains and buses) to O'hare and downtown. Please contact the hotel at 1-800-356-3641 to make a reservation and say you are part of the Midwest Primate Interest Group (do not reserve online). Room block expires September 2, 2010. There is also a nice hostel in downtown Chicago that offers discounted rates for groups of 10 or more. The hostel is close to public transportation that will take you directly to UIC.
Link to a general lodging, transportation, and restaurant guide