The new version (well, not new here but...) uses launchd and scutil so no extra software. We've been running it fine here on everything since 10.4 came out:

Click here to download the Cornell Namer.

Instructions:

Copy cornellnamer.plist to /Library/LaunchDaemons
Create /Library/AdminItems and copy cornellNamer.sh to this directory
Edit the dnsbase variable as appropriate for your domain

The script assumes that you have static IPs and a DNS that names each computer uniquely (in our case the name matches the asset tag for the machine)

cornellNamer.sh:

#! /bin/sh
#
# Cornell Computer Namer
# Modifications by
# Sam Agnew
# Weill Cornell Medical College in Qatar
# January 22, 2004
#
# Based upon
# Panther Post-Image Setup SPRING 2004
# ComputerName
# January 9, 2004
#
# Now launched via launchd
# Now using scutil
# Now using qatar-med.cornell.edu
# Sam Agnew
# July 31, 2005
# Minor cleanup for release November 9, 2005

test=$(ifconfig -a inet 2>/dev/null | sed -n -e '/127.0.0.1/d' -e '/0.0.0.0/d' -e '/inet/p' | wc -l)
# Max wait for network in seconds / 2
limit=60
# Set domain name base here
dnsbase=".qatar-med.cornell.edu"

# Set Initial Name and try to make it unique
TEMPNAME="Waiting-for-network${RANDOM}"
scutil --set ComputerName $TEMPNAME
scutil --set LocalHostName $TEMPNAME

# Wait for network
X=0
while [ $test != 1 ]
do
        echo Network not currently up
        test=$(ifconfig -a inet 2>/dev/null | sed -n -e '/127.0.0.1/d' -e '/0.0.0.0/d' -e '/inet/p' | wc -l)
        X=$((X+1))
        if [ $X -ge $limit ]; then
                break
        fi
        sleep 2
done

HWADDRESS=`ifconfig en0 | grep ether | awk '{print $2}'`
IPADDRESS=`ifconfig en0 | grep inet\ | awk '{print $2}'`
COMPUTERNAME=$(host $IPADDRESS | awk '{ print $5 }' | sed s/${dnsbase}.//)

###### IF COMPUTERNAME IS BLANK, SET NAME TO HWADDRESS, OTHERWISE SET  TO VALUE CALCULATED FROM DNS LOOKUP ######
if [ "$COMPUTERNAME" = "no" ]; then
    NONAME="`echo $HWADDRESS`-DHCP-Error"
    scutil --set ComputerName $NONAME
    scutil --set LocalHostName $NONAME
elif [ "$COMPUTERNAME" = "" ]; then
    NONAME="`echo $HWADDRESS`-Network-Connection-Failure"
    scutil --set ComputerName $NONAME
    scutil --set LocalHostName $NONAME
elif [ "$COMPUTERNAME" = "3(NXDOMAIN)" ]; then
    NONAME="`echo $HWADDRESS`-No-DNS-Record-For-Host"
    scutil --set ComputerName $NONAME
    scutil --set LocalHostName $NONAME
else
    scutil --set ComputerName $COMPUTERNAME
    scutil --set LocalHostName $COMPUTERNAME
fi

if [ $(who|grep console|wc -l) == 0 ]; then
    if [ $(ps wwaux|grep WaitingForLoginWindow|grep -v grep|wc -l) == 0 ]; then
        killall loginwindow
    fi
fi
killall syslogd

cornellnamer.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
        <key>Label</key>
        <string>edu.cornell.qatar-med.cornellcomputernamer</string>
        <key>ServiceDescription</key>
        <string>Names computer based upon DNS resolution</string>
        <key>RunAtLoad</key>
        <true/>
        <key>ProgramArguments</key>
        <array>
                <string>/Library/AdminItems/cornellNamer.sh</string>
        </array>
</dict>
</plist>