Ok,

Embarassingly enough, I didn't have 'ukphy' in my custom kernel, so
when I added 'gsip' it didn't get a PHY driver.

Now I am getting about 88Mbit/s receive/transmit between an 'epic' and
my new DGE-500T.

A nice new SMC 9462TX probes fine as 'gsip0', but doesn't appear to 
receive packets.  It is able to transmit successfully, as I see ARP
packets on another machine with tcpdump.  Perhaps related to this being
a 64bit card in a 32bit slot.  It does appear to be getting interrupts
though, according to vmstat.

-Andrew