Apple last week released AirPort 4.1 software for Mac OS X 10.3, adding a feature that's been in great need: the capability to use more modern and secure WPA (Wi-Fi Protected Access) encryption when you're also linking base stations wirelessly through WDS (Wireless Distribution System). This is common if you have an AirPort Express linked wirelessly to an AirPort Express or AirPort Extreme that's connected to the Internet. WPA is highly recommended, as the weaker WEP encryption has been broken for some time.
The update also includes necessary support for the new Keyspan Express Remote, which can plug into the AirPort Express's USB port to enable remote control of iTunes.
The update also enables you to rename a printer connected via USB to a base station. This solved a problem with the printer that my wife and I share at home; I could print wirelessly, but she had to remain connected via USB cable. After changing the name - its Rendezvous name, really - in the AirPort Admin Utility, my wife can now print to that printer. I suspect there's a funky entry for that printer deep in some Rendezvous .plist file on her machine that, if deleted, would have made it work, too, but this approach was easier.
The update also includes AirPort Express 6.1 and AirPort Extreme Base Station 5.5 firmware updates. AirPort 4.1 requires Mac OS X 10.3 or later, and is available through Software Update, or as a 12.4 MB download. An AirPort 4.1 update is also available for Windows; the firmware updates are also available as separate downloads.