I am interested in a motion detect feature that only triggers on the event of motion in a particular portion of the frame. It seems as if this already exists for CHDK(http://chdk.wikia.com/wiki/Motion_Detect_Plus (http://chdk.wikia.com/wiki/Motion_Detect_Plus)), and would be easy enough to port to magic lantern (Granted, I don't think I could do it myself). I think a lot of people would find this very useful!
After searching some more, it seems like A1ex may have already done this (http://www.magiclantern.fm/forum/index.php?topic=2879.msg12640#msg12640 (http://www.magiclantern.fm/forum/index.php?topic=2879.msg12640#msg12640)). However for the life of me I can't locate it. I am running the latest nightly build. If somebody could point me in the right direction, it would be greatly appreciated.
On my M1 I see it at Shoot -> Motion Detect
Try using the buttons that move the focus box.