I first heard about quilted multiverse, and landscape multiverse from Brian Greenes new book, Hidden Reality, I would reccomend reading it if you are into this sort of thing. I think they are some relatively new ideas, and it describes a lot of different multiverse models that seem to adhear to PCP. I think it was mostly an attempt to show conservation in multiverse string theories. I think they may have taken this conservation too far, and lost track what we observe to be the cosmological constant. I think this principle might actually prevent them from being able to find the cosmological constant in string theory. The principle in itself may directly violate the constant. The constant is that all galaxies are moving away from each other exponentially, not that an even number of galaxies are also contracting towards each other exponentially. If PCP where true, it makes it seem like the cosmological constant would have to come from more of an effect of conservation of the variation of the multiverse or universe. But, it is hard to imagine how the constant could be seen as just a variation when the universe is so homogeneous, because it is a pretty drastic effect on the visable universe, and it would mean that our part of the universe has gone to the extreme of expansion while maintaining homogeneity with respect to everything else. The principle just doesn't sit well with me because it doesn't fit the big picture on the movement of galaxies that I have read about. In Alan Guths Inflation, for example, he claims that the expansion of the universe if shown as negative that it could be conserved with the amount of matter in the universe. If that is true, PCP is an attempt at conservation then it may have just been applied incorrectly. The expansion would then have no need to have contraction in order to maintain conservation.
This paper talks about the homogeneity of inflation.
http://arxiv.org/pdf/hep-th/0702178v1.pdf
I lost track of Guths, 2004 paper, but I think that one talked about conservation in inflation, that I ment to link. I will try to find it. It was posted on sciforums not to long ago.
He talks about the energy of inflation and where it comes from at the end of 1.2
http://arxiv.org/pdf/astro-ph/0404546v1.pdf
Ah, the paper I was refering to that talks about inflation as a negative energy. 2001.
http://arxiv.org/pdf/astro-ph/0101507v1.pdf