Official OS X Lion 10.7.3 Build 11D50.
This Lion installer is unlocked so it can install onto Core Duo -> Core2Duo Upgraded Macs. Useful when you have only 1 Mac and cannot use a spare Mac to install Lion by Firewire Target Disk mode.
For Installation guide see Readme.txt. Just follow steps 1. -> 4. and your Lion install should go pretty smoothly.
If you have a regular Mac (hardware officially supported for Lion), then final post-install steps (3. and 4.) are not needed and can be ignored. Sorry we didnt mention that in the Readme file.