Well no one answered my question, but I found out that you can indeed pass the exam without taking a class. I read portions of the BarBri book and took three or four practice exams - did just fine.
I thought the test was rather difficult, but I guess I wasn't the only one who was unsure about a lot of the answers.
I guess only the local bar associations list the official passing scores, but there are a lot of sites that have tried to compile a list of all jurisdications. Here is one of those in case you're trying to figure out where you passed:http://www.micromash.net/BarReviews/MPRE.htm