Thanks for completely disregarding the question (when ML will ship on hardware).
What? Who cares about that? Its completely irrelevant when the hardware you buy online or in Apple Stores comes with Mountain Lion pre-installed. You will get Mountain Lion either way, free of charge. Whether your Mac already comes with Mountain Lion pre-installed or not. You just always get it.
I mean, thats the interesting part, right? It not like installing Mountain Lion is hard. You click download, install, done.
Thats how the rollout will work. Everyone who buys a Mac now gets Mountain Lion for free over the App Store, at some point (probably during August) all new Macs that are ship will just come with Mountain Lion pre-installed. The date is irrelevant since this is consequence free.