Kits are cool. I think it's just a way of saying "Use this if you write a desktop app and want to do X".
So if you want to program a app to work with devices.. you use devicekit! Then there is devicekit-power and devicekit-disk and such things.
I think that right now people are trying to find the correct layers of abstraction here... If you make the layers to think then the individual tools become way too complex and difficult to manage. Make the layer to high level and then application developers will avoid using your tools and then you get to many people running around making redundant and conflicting functionality. Make the layers to low and then you run into putting a high burden on app developers and you end up with conflicting functionality.
That sort of thing. I think that they are just searching around for the best way to do things before it all gets set in stone.