After upgrading from 1.4 to 1.4B/C, I get the following problem
on my macppc after rebuilding and reinstalling /usr/libexec/ld.elf_so
(kernel and libraries already rebuilt and installed):

telnet
Illegal instruction (core dumped)

This applies apparently to all dynamically linked programs :-(

A kdump/ktrace of telnet shows (keyed in by hand, beware of 
typos):

307 ktrace / several entries
             CALL execve
             NAMI "/usr/bin/telnet"
             NAMI "/usr/libexec/ld.elf_so"
307 telnet   EMUL "netbsd"
             RET execve JUSTRETURN
             PSIG SIGILL SIG_DFL
             NAMI "telnet.core"

reinstalling a binary ld.elf_so from 1.4 brings the system back to life.

 - Erik Bertelsen