From some angles i kinda like the sound of it, getting the scurge of society out doing good work in deprived countries, whether it is agriculture, irrigation, building services. It would also give them the chance to take a hard look at themselves and do some rehabilitation and realignment of their views seeing how many people struggle in this world.
I then wake up from my fluffy little perfect dream world and realise that this would be too hard to implement and they will all be playing on the playstations in their nice warm prison cells learning how to be better criminals!