They will work with any switch, but only at 10Mbit. It merely depends upon how brain dead your network switch is. If it's a decent one then without being able to negotiate the connection it should default to 10Mbit, which is what the old 10BaseT hubs ran at.
I had my SE/30 connected to a gigabit switch with no issues.
I did not really understand, why the powerbook was needed as an intermediate node in this example.
I have two SE/30s, one with a working Asante Ethernet Card. So with the Asante local talk bridge and the local talk phone net adapter I should be able to connect my 2nd SE/30 to the net like Stephen_Usher mentioned?
Cool! So can I use a serial printer cable to connect the two SE/30s and then install the local talk bridge extension on the ethernet mac and everything will be fine? What about TCP/IP on the mac without the ethernet, how will I get internet connection?