Installed it on 2 Xserves....
GOT AN EXTRA ETHERNET PORT ON BOTH????
When you run ifconfig, the en0 MAC address is duplicated in en2.... (the optional 1Gb ethernet network interface is also installed: en1)
In the GUI the "network' control panel says "new network port found"???
FYI: the Xserves are the "original" Single 1 GHz and the Dual 1 GHz Xserves....
Don't know on a desktop G4 though. Try it later.