You can share a printer with computers on your network by connecting it to an AirPort Extreme Base Station's USB port. The printer will be available to computers via Bonjour (formerly "Rendezvous").
If two printers with the same model name are connected to two base stations on the same subnet and you're using older AirPort firmware, you won't be able to tell which printer is which when you select one in Printer setup, nor can you rename them.
Later versions of AirPort software and Firmware resolve this issue. Use Software Update or Apple Downloads to get AirPort 4.1 or later software, which will include updated base station firmware (5.5 or later for AirPort Extreme, 6.1 or later for AirPort Express). Once AirPort 4.1 software is installed on your computer, update the firmware on the AirPort Extreme Base Station or AirPort Express.
After both software and firmware are updated, you can rename the printers in AirPort Admin Utility. Be sure that you give each printer a unique name. The new names will appear on the network, and computers will be able to distinguish between them.
Tip: On larger networks, give each printer a name that corresponds to its base station or location.