I recently upgraded to samba-2.0.5a-1.sparc and found that
install-scripts adding the swat service in /etc/services
changes the permissions of that file to -rw------- (whence
trouble for mortal users using tcp services afterwards).
(The script actually does not touch the perms, but creates a
tmpfile which is later moved to /etc/services).
I did not try what happens on other architectures.
Fixed (mostly, upgrades on old packages may still have a problem
under certain circumstances) in samba-2.0.5a-10.