…and of course there is this:
In the meantime, if you’re reading this, chances are good that you have a fast broadband connection; feel free to stop reading right now, launch the Mac App Store, and start your multi-gigabyte download before continuing. What you’ll be rewarded with at the end is an icon in your Applications folder labeled “Install Mac OS X Lion.” (See?)
Once you have the installer application, you could (were you so inclined) dig into it (control-click, then Show Package Contents) and find the meaty center, a 3.74GB disk image (InstallESD.dmg, stored in the Contents/SharedSupport folder). You could then use that disk image to, say, burn a Lion installation DVD or create an emergency external boot disk.