The restore procedure will take anywhere from five to 15 minutes, depending on your Mac and the speed of your drive.
If your only Mac was released after Lion, so you can’t download the Lion installer from the Mac App Store, I’ve also provided instructions for creating a bootable Lion-install drive for newer Macs.
So if you create a bootable Lion-installer drive using the current version of the Lion installer-which, as of, installs OS X 10.7.3-that drive will work with all current Lion-capable Macs. However, unlike with the CD- and DVD-based Mac OS X installers of old, Apple can-and does-update the Mac App Store version of the Lion installer. Update: When this article was originally published, the Mac App Store version of Lion would not boot any Macs released in mid-2011 or later, as those models shipped with a newer version of Lion preinstalled.