Cananadian arms company created a 20 ga "sock round"and a 20 ga 5shot revolver, also watch the second video they have an enhancedd flash and bang round for entry teams... http://www.infowars.com/?p=1000
I would have to say that unless its for something like prison guards, there really isnt any use for 'less than leathal' ammo in current times. In times long past (and possibly post SHTF) something along the lines of the 'rock salt' loads could be used for trespassers or chicken thieves. In our current world though A)you point a gun at someone they dont know what loads it has so if they are armed then its the time they will feel they HAVE to kill you or surrender if its an offered option B)if you shoot them with it and were not justified to use deadly force then your probably going to jail C) if they survive they will try to make you out as the bad guy so they distract from what they did to earn it D) if they live you are most likely their new slave after they win the lawsuit against you for hurting and traumatizeing them. So at least to me, it seems like the best bet is that if you have to use force at a level that you need a weapon then your best bet is to use good ammo that will stop them permenantly...besides it saves the tax payers more money.
Exspect it to be used against demonstrators(like the not always less than lethal "rubber bullets"..).
a cop once told my mom after our house was broken into, that you should shoot them center mass, then drag them into your house, before they start bleeding too much, if not already there. That way the use of deadly force is authorized. They say it saves them alot of pain and paperwork.