I am dealing with this, too. My son is a super light sleeper and very particular about things, so I am quite sure if he rolled over or something, we'd hear about it in about 1.5 seconds.
As for weaning, some people do 1 arm out for a little while, then both arms. DS is 5.5 months and still needs to be swaddled fully so I'm really no help there!
Mumma to DS July 2010 and expecting another baby boy late July 2012