uh, ok.
When I went there and the admissions person was talking, she said that they look at your core academic classes, and they take each grade, and use their own system to give you a GPA (based on JHU terms). BUT, they eventually factor in honors/APs (they have to...they're not going to take someone who has straight As in the easiest courses), and from there they decide and stuff...
If you want more info:
Hopkins Forums -> Questions about GPA / Class rank
I had the same question and this thread helped me out a lot.