I dealt with this issue at Oakland University (through involvement with Students for Concealed Carry). The above comment is correct. Colleges and universities can make "rules" for faculty, staff, and students because they have entered into a contract to attend/work for the school(much like any other employer). However, Preemption does apply with respect to the general public. For example, if I were to walk on to MCC's campus carrying my firearm (not being a student or employee of the college), they can't really do anything (at least legally). Likewise, you could walk onto OU's campus carrying without fear of legal sanctions. Conversely, if you were to carry a gun onto MCC's campus (as a student), and you were found by campus security to be carrying, the college could not do anything legally (you would not be in violation of any state or local laws as long as you aren't carrying in state pfz's). However, they could hand out administrative punishment (ie, kick you out of school).
In my experience with SCC, it was explained to me that if the legislation, that has been proposed to remove PFZ's for cpl holders, is passed then colleges and universities may be compelled to change their rules. Because college classrooms and dorm rooms are on the list of places you can't carry concealed, schools have a stronger argument for their weapons bans.
If you are interested in this subject, I would highly suggest you look into Students for Concealed Carry
http://concealedcampus.org/] [url]http://concealedcampus.org/[/url]