People might be interested in DoubleDown (http://blog.devstructure.com/introducing-doubledown http://blog.devstructure.com/introducing-doubledown) from the DevS

People might be interested in DoubleDown (http://blog.devstructure.com/introducing-doubledown http://blog.devstructure.com/introducing-doubledown) from the DevStructure guys. It uses rsync in a similar background manner and it's designed with this exact problem in mind.