Existing users, 
AirPort Utility 5.0 (note the name is NOT "AirPort Admin Utility") ships with the new Extreme Base Station that was released in Feb '07. Details here.
AirPort Utility replaces both AirPort Admin Utility and AirPort Setup Assistant.
Apple AirPort Base Station Update
for AirPort Utility 5.0
Version: 2007-002
AirPort Utility 5.0...
Feedback Type: Usage Tip
Contributed by: Andreas.. Thursday, March 29 2007 @ 06:07 PM PDT
Product Platform: MacOSX
Used Product For: 1-6 months
Comments
AirPort Utility 5.0... - mtcon
It may not make any sense but Andreas is correct. Apple needs to do a better job of explaining their updates.Thursday, March 29 2007 @ 06:29 PM PDT
Don't make it even more confusing... - Andreas..
I explained what AirPort Utility 5.0 is. I did not explain what the update is for. One doesn't contradict the other.Thursday, March 29 2007 @ 06:32 PM PDT
AirPort Utility 5.0... - frankiecheezoli
"...and AirPort Express Base Station..."AirPort Utility 5.0 didn't come with my AirPort Express.
SO HOW DO I GET IT?
Thursday, March 29 2007 @ 07:37 PM PDT
AirPort Utility 5.0... - Steve West
The updater contains a full copy of Airport Utility 5.1 which you can extract:Double-click AirPortBaseStationUpdate2007001.dmg to mount and display it's contents.
From the AirPortUtilityUpdate window, right-click on "AirPortBaseStationUpdate2007001.mpkg."
Select "Show Package Contents" from the pop-up menu.
In the "AirPortBaseStationUpdate2007001.mpkg window, double-click on the "Contents" folder to open it.
In the "Contents" window, double-click on the "Packages" folder to open it.
Right-click on "AirPortUtility.pkg."
Select "Show Package Contents" from the pop-up menu.
In the "AirPortUtility.pkg window, double-click on the "Contents" folder to open it.
Double-click on "Archive.pax.gz." This will create a new folder on your Desktop, named "Applications." The AirPort Utility will be inside this new folder. You can copy or move it to your Utilities folder.
These instructions come from the website of James Clay:
http://homepage.mac.com/james.clay/iblog/B894479528/C2040813928/E20070505184135/index.html
Thanks James, it worked for me.
Wednesday, July 04 2007 @ 09:53 AM PDT
AirPort Utility 5.0... - eatapc
This makes no sense. Apple says, "The AirPort Base Station Update 2007-001 includes general fixes and compatibility updates for the following applications: AirPort Utility, AirPort Admin Utility for Graphite and Snow Base Stations; AirPort Disk Utility; AirPort Disk Agent." It doesn't say anything about updating only the utility that ships with the new Extreme.Reply to This
Thursday, March 29 2007 @ 06:12 PM PDT