Some of the stuff (e.g., rarpd, bootpd, dhcpd etc., libsa) still will only support Ethernet. Tcpdump itself should be ok, but libpcap needs lot of work. For the detailed change history, look at the commit log entries for the is-newarp branch.
I did not add them to the library, but rather compile them where the netboot program is built so I can add -DSUN_BOOTPARAMS, etc.