Comments on USB-Equipped Ethernet Print Servers?

An Anonymous Coward asks: "I'm looking to purchase an external Ethernet print server with an USB printer interface. I've only found two such beasts HP JetDirect 175x and Sercomm PS5800). Do I have any other hardware options? Do USB print servers work with any USB printer, or are there driver issues?" Comments, anyone? Information about running such a box under free operating systems would also be nice.