Apple has posted AirPort Utility 5.5.2. You can obtain it via the Software Updates component of Mac OS X’s Systems Preferences app.
The 10.29MB download requires Mac OS X 10.5.7 or later and contains bug fixes and improvements, including the following:
° Resolves an issue that caused the DHCP settings tab to display incorrectly;
° Resolves an issue that caused the application to quit unexpectedly when automatically launched;
° Resolves an issue that prevented the network password from being stored in the Keychain when the network on the 5GHz band was named differently.