About the topic its self, I think a PPA would be a bad idea, at least at this time. I am not sure how much help users will be who can not learn how to compile, I think we are likely to just get flooded with bug reports, likely poor quality ones, that more relate to where development has not yet happened rather than real bugs.
Also having a PPA that will quickly become obsolete and meaningless once the branch reaches master sounds likely to confuse users to me, they likely will end up with more than on FreeCAD, one of which is obsolete. So you would need some way of automatically deleting the PartDesign New FreeCAD from someone's system once it has been merged.
Others may disagree, but I just see this as another way to make the less knowledgeable even more confused ...compiling FreeCAD on Kubuntu is not difficult, a lot of us learnt how to compile due to a desire to compile FreeCAD. We should rather encourage those capable to learn how to compile mostly by having clear up to date instructions in the wiki. Obviously I am generalising but really, how much help can someone be who will not learn how to do something as easy as compiling FreeCAD on a Ubuntu variant? Once you get to near release quality code that would likely change because you want all the use (but that code would by then be in master) and reports you can get but in the earlier development stages there might become too much time spent on the less experienced users that ends up sidetracking those trying to do the development.
But anyway if you guys are to do this, don't forget to reconfigure the PPA so that using your new PPA would no effect the other FreeCAD Daily or stable PPA. You should also consider how the system will associate which FreeCAD with fcstd.
I doubt you will be able to resolve all the dependency issues including c++11 to get it to work for 12.04, which will not "end of life" until a year and a bit from now.
So in summary I think that at best it will be a lot of work for very little benefit, but don't let my negativity stop you guys, if you are prepared to do the work.