You need to copy that MacOSX.dmg to your desktop or somewhere on your machine, then change the hidden flags

open  "/Volumes/Mac OS X Install/MacOSX.dmg"

You can also use hdutil on this as well to mount the image. However, given my time crunch of it needed to be done yesterday this was my very first draft on how to do it. By all means you are correct, this could have been a bit smoother I won't argue that

Hey dude, where do you work that every employee gets an MB Air? It must be a very good workplace then, I must apply there :)

Very useful info, I have had to do this another way by downloading Mac Mini/Air Builds from App Store (Not forking out for Apple USB recovery keys!) using Recovery HD and hard shut down before it installs then extract the InstallESD.dmg file to create my images from and the firmware password tool and use the Magic of Deploystudio for the rest.

As such the lack of media is a problem for most users and I urge you to immediately create
1) A Lion recovery disk from USB Flash drive and put it somewhere safe http://support.apple.com/kb/dl1433
2) If you can make a proper install flash drive with full installer on then even better, so you do not have to wait for download again !
3) A complete TimeMachine backup before you do anything or a ASR disk image as it out of the box.
There are a few ways.... that Apple has made us jump through hoops for the privilege of installing their OS !

They really dropped the ball on this one. I managed to get into a right pickle (Bricked Mac) a few weeks ago after creating a RAID set on Mac Mini Server and the USB recovery disk did not work correctly (Kernal Panic), internet recovery from UK was not having it. Luckily i was only 15 mins walk from AppleStore. After an hour or so explaining my way up the chain of command past the super-genius's to the Manager.....he swapped it.

I might add most people had no idea what a machine specific build was and the fact that the key they were trying to sell me would not boot the Mac Mini or Air anyway.

I am in the middle of mass deploying thousands of new MacBook Airs at work...

Is your company hiring? Please?

I wish, I could actually use some help supporting these things

I copied the command line binary into my image and baked it with InstaDMG. I put the binary in the standard $PATH and kept all permissions the same, root:wheel 700, and now I can script out changes and deploy them while my Macs are in the field. I can also mass deploy during imaging.

Hope this helps

This worked for me on my mid-2010 MBP running Lion.
Interestingly, running "setregproptool -c" *does* clear the password, and did *not* require me to authenticate in any way whatsoever.
Of course, I was already logged in, but still, if you run the GUI version it *does* make you enter your user password first.
Slack, apple, slack.

$ sudo hdiutil attach -readonly "Install Mac OS X Lion.app"/Contents/SharedSupport/InstallESD.dmg
$ sudo hdiutil attach -readonly /Volumes/"Mac OS X Install ESD"/BaseSystem.dmg
$ sudo /Volumes/"Mac OS X Base System"/Applications/Utilities/"Firmware Password Utility.app"/Contents/Resources/setregproptool -h
setregproptool v 2.0 (9) Jun 16 2011
Copyright (C) 2001-2010 Apple Inc.
All Rights Reserved.

Usage: setregproptool [-c] [-d [-o <old password>]] [[-m <mode> -p <password>] -o <old password>]

    -c              Check whether password is enabled. 
                            Sets return status of 0 if set, 1 otherwise.
    -d              Delete current password/mode.
                            Requires current password on some machines.
    -p              Set password.
                            Requires current password on some machines.
    -m              Set security mode.
                            Requires current password on some machines.
                            Mode can be either "full" or "command".
                            Full mode requires entry of the password on
                            every boot, command mode only requires entry
                            of the password if the boot picker is invoked
                            to select a different boot device.

                    When enabling the Firmware Password for the first
                    time, both the password and mode must be provided.
                    Once the firmware password has been enabled, providing
                    the mode or password alone will change that parameter
                    only.

    -o              Old password.
                            Only required on certain machines to disable
                            or change password or mode. Optional, if not
                            provided the tool will prompt for the password.
$

Also, one caveat with this is that if you disable it, the last command output will still be 0 until you reboot. Since the binary itself should return 1 if the firmware password is not set with the -c option.