HalfDomeHike: The MR is for people seeking a greater adventure then what the trail offers. Much of it is just cross country (class 2) following a thin use trail. I personally would not do a one day hike up the regular trail, even with a permit. It is just too long, especially on the way down.
There are class 3 sections which do involve some exposure and hands on climbing.
There are many good pictures available and discriptions.
I took my whole family up the MR last year, including 2 nine year old twin boys. Of course I was there the whole way, telling them where to climb and what to hold on to. It helps to know where you are going.
http://client.webshots.com/album/221318818YvtQVKBeach has some good links, which will help you fill in the blanks.
http://www.mt-whitney.info/viewtopic.php?t=126