I've visited this one a time or two in my Mac 911 column, but I continue to get enough email on the subject of connecting legacy printers to new Macs that it's worth addressing again.
If you have an old LocalTalk printer -- an ancient Apple LaserWriter, for example -- you can continue to use it with the help of an adapter such as Asanté's $130
Ethernet to LocalTalk Adapter . Such an adapter sports an Ethernet port on one end and a LocalTalk (serial) port on the other. To make the connection, string a standard Ethernet cable between your Mac, hub, or router's Ethernet port and the adapter and a LocalTalk cable between the adapter and the printer. Print Center/Printer Setup Utility will see the printer as an AppleTalk device.
If you're not sure if your Apple printer supports LocalTalk, this specifications page on Apple's website will tell you.