Having had sendmail installed on your system could result in suid
binaries via a variety of paths. I expect to be seeing CERT
advisories on sendmail into the next millennia.
If you're concerned about such things, you might want to keep an eye
on the list of suid programs. Presto, no kernel changes needed, no
need to break any standards, etc.
find `grep ^/ /etc/mtab | awk '{print $2}'` -mount -type f -perm +4000
-- Raul