I think the most important thing Blake mentions here is the amount of customization required per network. Obviously, each system is not the same: they have different features, conventions, permissions, etc. But it'll be interesting to see whether or not developers can keep one application in its own branch in source or will they literally have to have multiple instances, one for each network.
If development feels like doing one app 14 times instead of one app once, that'll suck, but at least things will be familiar when you are duplicating code. Interesting to see how well this works. Roll, Google.