Premed, I think there are faq's that can give you a better answer to this and any other questions you will have.
However, I will make a (feeble, probably) attempt.
Part of it depends on what kind of program you are looking at. There are formal and informal programs. There are programs that offer linkages (direct entry to a specific medical school upon successful completion of the program) and those that don't.
I have seen rough cut-offs of 3.5, 3.0 and 2.5 to get into a program.