You're probably already running an ipchains firewall. You can't use both at 
the same time, therefore the iptables init script exits immediately if it 
notices ipchains is in use.

I don't think that ipchains has anything do with it.

First of all, this is a stock 7.1 box set up with no firewall and no ipchains
rules.

Second, when I turn off ipchains using chkconfig and stop the ipchains service,
I get the same result. See this chains of events:

[root@bleach /root]# chkconfig --list ipchains
ipchains       	0:off	1:off	2:on	3:on	4:on	5:on	6:off
[root@bleach /root]# chkconfig ipchains off
[root@bleach /root]# chkconfig --list ipchains
ipchains       	0:off	1:off	2:on	3:off	4:off	5:off	6:off
[root@bleach /root]# service ipchains sto 
Usage: /etc/init.d/ipchains {start|stop|restart|status|panic|save}
[root@bleach /root]# service ipchains stop
Flushing all chains:                                       [  OK  ]
Removing user defined chains:                              [  OK  ]
Resetting built-in chains to the default ACCEPT policy:    [  OK  ]
[root@bleach /root]# service iptables sadfsad
[root@bleach /root]# chkconfig --list iptables
iptables       	0:off	1:off	2:on	3:on	4:on	5:on	6:off
[root@bleach /root]# service iptables restart
[root@bleach /root]# more /etc/sysconfig/ipchains 
/etc/sysconfig/ipchains: No such file or directory
[root@bleach /root]# 

It just seems like "service iptables (whatever)" should give you some sort of
feedback, anything, even to say that ipchains is active and iptables cannot be
started.

I mean, I can even see the line in the iptables script that should be output
when a random parameter is passed to the script (it reads echo $"Usage: $0
{start|stop|restart|condrestart|status|panic|save}"). But no matter what I do,
what I turn off, or whatever, I cannot get iptables to give me back that line.
ipchains gives it to me fine. Just not iptables.

Please let me know if I am being an idiot. Thanks.

I encountered the same problem. The iptables script makes it pretty clear:
start() {
        # don't do squat if we don't have the config file
        if [ -f $IPTABLES_CONFIG ]; then
          ....
        fi
}

However, no default config script (/etc/sysconfig/iptables) is created when the
package is installed.
[root@thunder /root]# ls -l /etc/sysconfig/iptables
ls: /etc/sysconfig/iptables: No such file or directory
[root@thunder /root]# rpm -q iptables
iptables-1.2.1a-1
[root@thunder /root]# rpm -ql iptables | grep sysconfig
[root@thunder /root]#

However, if I do..
[root@thunder /root]# service iptables save
Saving current rules to /etc/sysconfig/iptables:           [  OK  ]
[root@thunder /root]# service iptables start
Flushing all current rules and user defined chains:        [  OK  ]
Clearing all current rules and user defined chains:        [  OK  ]
Applying iptables firewall rules:                          [  OK  ]
                                                           [  OK  ]
[root@thunder /root]# 

All is fine.

I actually found this yesterday as well (but I hadn't gotten around to posting
it on Bugzilla yet).

In addition, I had to rmmod ipchains to be get the iptables module loaded to
turn iptables on. Of course, ipchains and iptables cannot both be functioning in
the kernel at the same time. Then, why it is possible to enable both "services"
at a particular runlevel? Should iptables check to see if ipchains is already
configured to run at that runlevel and refuse to turn itself on if it is? (And
vice versa?)

1.2.2-3 adds warnings explaining why nothing is being done.