Also, I'm curious how Launchpad gets populated. If it's iOS-like, the Folders in it won't reflect the real file system. But then how will apps already in file system folders (e.g., Utilities) appear in it? I saw System Preferences on there, so it must work, but I want to know how.
I suspect it will simply be a configuration file in the user's Library folder. Each entry will point to a real app in the filesystem and include any information about where it resides in the user's Launchpad. Much like the Dock can be rearranged at will, not affecting the underlying locations of apps and folders in the filesystem.
Actually, the Launchpad is really just a giant full-screen Dock when you think about it. Though I wonder if it will have the same kind of right-click menus and things for app icons; probably not, at least initially.